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|Japanese name:|| 世良 真純|
|Relatives:|| Tsutomu Akai (father, deceased)|
Mary Sera (mother)
Shuichi Akai (older brother)
Shukichi Haneda (second-older brother)
|Occupation:|| Teitan High School Student |
|First appearance:|| Manga: File 768|
Anime: Episode 646
|Appearances:|| Chapters: 83|
|Keyhole number:||Volume 73|
|Japanese voice:||Noriko Hidaka|
Masumi Sera (世良 真純 Sera Masumi) is a high school detective in the manga and anime franchise Detective Conan. She is the younger sister of FBI agent Shuichi Akai and a practitioner of the martial art Jeet Kune Do.
Masumi Sera is a high school detective and the younger sister of FBI agent Shuichi Akai and shogi player, Shukichi Haneda. She is the only daughter of Tsutomu Akai and Mary. 17 years ago, her father, before he disappeared, instructed his family to hide in Japan, where Masumi later was born. Her oldest brother had prior to her birth left Japan to study in America, so they first got to meet each other when Masumi was six-seven years old. Although she grew up in Japan during her elementary school years, she moved abroad three years ago with her mother, presumably due to Shuichi infiltrating the Black Organization. Her other brother stayed in Japan. She has recently returned to Japan for some unknown reason. After meeting Conan, Ran, and Sonoko during a case, she transfers to Ran's high school class. Masumi is skilled at Jeet Kune Do, a hobby encouraged by her brother Shuichi who mailed her instruction videos while in elementary school. She can fight on the same level as Ran. She seems to know that Conan is Shinichi and she had in fact met Ran and Shinichi sometime in their past. Currently she is living with Mary, whom she calls "Mama", at a hotel. She claims that she is provided for by a rich friend of her late father, but it hasn't been revealed who it is. Every time they encounter the possibility of information on Mary getting out, they end up moving to a new hotel under Mary's order. While Masumi is eager to seek help from Conan, Mary is skeptical of him. The three siblings has different last names. Sera is supposedly her mother's maiden name.
Masumi has a cheery, sociable, boyish personality and is well liked by her classmates at Teitan High. On their first meeting, Masumi fails to correct Sonoko's mistaken impression that she is a man and even makes it worse by declaring that Ran is "[her] type". Her rather boyish appearance - especially in relation with her flat chest - is a bit of a touchy subject to Masumi, who claims that her mother's bust size is rather well developed and keeps expressing her hope that someday her own chest size will similarly change for her.
Masumi is quite quick-minded, coming up with clever plans and adapting them to sudden changes rapidly. Masumi seems to be prone to dramatics like most detectives are, but perhaps to a lesser degree than Shinichi or Heiji as she bluntly says who the criminal is without preamble. On the other hand, Masumi is tough to the point that she is willing to risk all to achieve a successful conclusion of a case. In one instance, she purposefully lured a hostage-taker into a sniper's sight with a smile, hoping he would be shot without showing any apprehension about his possible demise.
Although she has crime scene experience, Masumi seems to be less skilled as a detective than Shinichi or Heiji, apparently missing a critical clue that was necessary to understand how the murderer's setup worked, although Conan opines that Masumi purposely made an error in order to test him. In some degree, she seems to like rivalry or contests to see who is the winner.
Sera's catchphrase upon the conclusion of a case is "case closed".
Sera shows a protective and caring side towards Conan, as seen in the Detectives Nocturne and in the beginning of the Red Woman case when she helps Conan up after falling, as well as having it made clear in the Haunted Hotel case that she was also clearly investigating Conan before they first met, as she knew he was a detective. Its likely to believe that them being on the same bus was not an accident, which could even lead to be argued that she somehow hinted to them about the cake buffet so they would be on the same bus as her. It is safe to assume though she was, and possibly still is, investigating Conan.
Sera's way of referring to her parents as 'Mama' and 'Papa' indicates a privileges background.
At first, she wears a grey fedora that used to belong to Shuichi Akai and a dark jacket which gives her an androgynous appearance. When she transfers to Teitan High, she gets rid of her fedora and wears female clothing. Her hair is dark, wavy, and short; it doesn't even touch her shoulders. Even then, she is rather tomboyish; Genta mistakes her for a man, and Sonoko comments she has a petite figure. Later, Genta, Mitsuhiko and Hattori comment that her bosoms are rather small. Masumi also has an uneven tooth that shows when she smiles.
Masumi and her brother Shuichi presumably more closely resemble their mother than their father.
 Plot overview
 Masumi's Introduction (Manga: 768 - 770, Anime: 646 - 647)
Masumi first met Sonoko, Ran, and Conan on a bus after she was mistaken for a groper. After Sonoko declared Masumi was the groper, Masumi and Ran got into a fight, with Masumi's Jeet Kune Do holding even against Ran's karate. Conan and Masumi cleared up the misunderstanding by pointing out the real groper. Sonoko then mistook Masumi for a boy, an impression which wasn't helped by Masumi declaring that Ran was "his type". Masumi and Ran both discovered they were heading to the same hotel, about which Conan is less than pleased.
Masumi finds out the hotel she is staying at doesn't have a room available and complains at the front desk. A man then falls into the parking lot and dies. Conan runs to the source of screaming while Masumi told the guard to watch the elevators before running to the roof. She immediately declares the crime to be a murder, giving her reasoning. She then reveals her name, Masumi, that she is a detective, and knows Conan is a detective as well. She also revealed before she knew Conan's name despite it not being mentioned in front of her, revealing that Masumi has been investigating Conan for awhile now.
Inspector Megure is not pleased to have another high school detective underfoot but lets Masumi and Conan investigate regardless. After listening to the suspect testimony, police observations, and examining the crime scene, Masumi announces that she has solved the case.
However, Masumi's deduction leaves out a critical detail; Conan is therefore forced to use Shinichi's phone to call his own, give Inspector Megure Conan's phone, and speak through Shinichi's as Shinichi using the voice-changer bow tie. Shinichi figures out the detail that had Masumi stumped, although a look she gives Conan as he runs off suggests her omission was possibly intentional, and once during the phone conversation she tries to trick Shinichi into admitting that he is physically present at the crime scene instead of being explained the details by Conan and Megure.
The following day, Masumi transfers to Teitan High School, surprising both Ran and Sonoko. She was rather popular at school surrounded by students asking her questions about herself.
 Let's hear your brilliant deduction! (771)
According to Sonoko, Masumi has become very popular at Teitan high for being "cheery, sociable, boyish, and cute...and on top of that, she is a jeet kun do-using female detective!" One classmate compares her to Shinichi Kudo who has been taking a break from school. Masumi tells inquiring classmates that she has been staying in America with her parents since three years ago, but "rebelled" because she would rather live in her Japan where she was born and raised. She sneaks up behind Sonoko and Ran after school because she wanted to speak to Conan at the Mouri Detective Agency. At the agency, Masumi is unhappy to hear that Conan and the rest of Detective Boys are staying at Agasa's house and will be camping the following day. She settles for asking Kogoro if Conan is always at his side when he solves cases, hinting that she suspects Conan is the real brains behind "Sleeping Kogoro".
Just as Masumi is about to walk out the door, three female mystery writers and a man enter the agency. After a moment of confusion, the man suddenly fires a gun into the roof and takes the detective agency hostage. His demands are that Kogoro figure out which of the three writers killed his sister at a ryokan one month ago. The quick thinking Masumi sidles up to Ran and tells her to go for the man's gun after she takes his legs out. Sera's leg sweep sends the man to the floor, and Ran removes the gun from the man's hand with a kick; however, Masumi leaps back when the man reveals he has bombs strapped around his chest and will detonate them if they try to stop him.
Meanwhile at Agasa's, Haibara is angry that Conan used Shinichi's voice to solve a case around the suspicious Masumi. Conan's response is that Masumi is familiar somehow, like they have met before or she looks like someone, and Conan feels she isn't an enemy. Genta and Mitsuhiko told Conan they saw a high school student walking home with Ran, so the jealous Conan calls Ran's cellphone to hear about it from her.
The hostage taker man orders Ran to answer her phone, but Masumi snatches the phone away and says hello to Conan (who is shocked that Masumi is with Ran). Masumi then tricks the hostage taker and keeps the line connected so Conan can listen in by closing Ran's Sea Cucumber Man cellphone strap in between the screen and keypad of the the flip phone.
 Nickname Rules (772)
Masumi asks a few insightful questions about the case; however the hostage taker man discovers Ran's phone is still connected. Under gunpoint, Masumi steps in front of Ran and takes the blame, but Conan, using Shinichi's voice, says he ordered Ran to do it. Masumi is mystified by why Shinichi is now on Conan's phone. Masumi meanwhile spots a glint of light across from the detective agency and declares that the case will come to an end without Shinichi's help.
 Possible Sniping (773)
Masumi explains to Ran that she secretly kept the call to Conan connected so he could call the police and research into the case. While Masumi is still surprised that Shinichi was on the other end of the line instead of Conan, she had initially hoped that Shinichi would somehow be able to talk down the would-be-murderer. She suspects that Shinichi has already figured which one of the suspects is the murderer in the ryokan case, but Shinichi is unable to reveal the truth because the hostage taker would then kill the named culprit and then himself. Sera's plan changed when she noticed the lights from the police snipers on the building across from Mouri Detective Agency. She explains to Ran in detail the names and functions of the various police divisions responsible for hostage situations, and tells Ran in a roundabout fashion that this situation will end with the hostage taker being killed by the police.
Masumi launches a plan to bring the hostage taker into the snipers' range by telling him he should charge Ran's phone battery. Ran foils Sera's intentions by shutting the curtains, blocking the snipers' shot. To Masumi's utter astonishment, Ran tells her that she doesn't want to see anyone die in front of her and declares that "Shinichi won't allow anyone to die. He absolutely wouldn't!"
 The book with unturned pages (774)
Masumi and Ran take the opportunity to disable the hostage taker when he loses his composure and grip on the detonator after Shinichi tricks him into believing his sister committed suicide. Masumi yells for the waiting bomb squad to secure the area. With the hostage taker arrested, Shinichi then reveals the true culprit. Masumi realizes the mistake in her deduction and explains the correct timeline of events before the murder. Sometime soon after the conclusion of the case, Masumi, walking with Ran and Sonoko speculates aloud that there must be some reason Shinichi left Agasa's before Ran could meet him there. She then exclaims that "due to what just happened, she really gets it", that Conan and Shinichi are on very good terms with one another, and that Ran "is tougher than Masumi thought". Conan isn't sure what to make of these last comments.
Masumi stops Genta and Mitsuhiko outside of Agasa's house to ask them if they are acquaintances of Professor Agasa. The topic of Shinichi comes up when she talks to Mitsuhiko and Genta about the prior hostage case. Mitsuhiko mentions that Haibara told them to keep Shinichi's involvement secret. After asking about Haibara, Masumi mentions that she saw Haibara in one of the professor's online videos. Next, Masumi asks who is currently living in the Kudo house because she saw the curtains shift slightly. The Detective Boys tell her that Subaru Okiya has been staying there since his apartment burnt down. Masumi cryptically comments with a smirk on her face, "And here I thought that someone had just settled in without permission...But it seems I was just getting worked up over nothing..." while looking up at where Subaru is hiding.
At the end of the case, Masumi is in her hotel room deleting various files. One of her deleted files was a still image from Agasa's video blown up to show Haibara reflected in Agasa's glasses. This indicates that she is not only keeping an eye on Conan but also on Haibara. "Delete... Delete... For data, at least is an easy task to accomplish...", were her words while she was doing it.
The case opens with Ran talking to Masumi about Heiji Hattori who is stopping by for a visit. Masumi is curious whether Heiji or Shinichi is the better detective. After Heiji is introduced to Masumi, Kazuha then calls Heiji and tells him that she is stuck at a restaurant because someone died and a foreigner Andre Camel is keeping everyone from leaving. Masumi proposes Heiji and Shinichi (via Conan's cellphone) have a deduction match. At the crime scene, Masumi becomes curious about the foreigner, Camel who secured the area. The police and Conan reveal Camel is an FBI agent and Masumi takes interest. Meanwhile, Camel finds that Masumi looks familiar, but can't quite place why. He takes a picture of her and mails it to Jodie and James Black who are waiting outside. Jodie and James think Masumi resembles someone too, but only James Black correctly identified Masumi as female.
Meanwhile Masumi is busy helping with the case, asking questions and making comments about various deductions. Heiji nearly slips up with Conan's identity in front of her earning a pointed question from Masumi, but Heiji rescues himself by saying he thinks of Conan as Kudo when Conan gets smug have hearing Shinichi's deductions over the phone. Masumi doesn't seemed to be fooled though, her thoughts show that she seems to know Conan, not Shinichi, is the one solving the case while watching Conan come to his final conclusion.
Conan, Heiji, Masumi, and the rest of the group return to the Mouri Detective Agency after the poisoning case at Danny's restaurant. Heiji reveals the case that brought him to Tokyo; he received a mysterious letter signed in the name of a person who was murdered in Karuizawa requesting an investigation. Masumi takes an immediate interest in the case and wants to tag along, but Heiji refuses saying that the people he is visiting are only expected five people. Masumi is peeved at being left behind.
Masumi is walking with Conan, Ran and Sonoko. While they wonder why Kogoro has been coming home late, Sonoko thinks he's found himself a mistress. Masumi thinks that he is just investigating a case. When an old lady named Takae Kiritani comes, she claims that Kogoro has been helping her. Masumi asks what he does for her to which she replies that its small things like helping around the house. Masumi isn't seen again for the rest of the case.
During a murder case at Mouri Detective Agency, after meeting Kogoro's new apprentice Tooru Amuro, Megure comments that the number of detectives around Kogoro has increased again, referring to Masumi. Amuro takes interest in Masumi. Later, Kogoro and friends go over to a suspect's apartment. Masumi calls Ran after hearing about the murder on the news because she is worried about her and Conan. The call has an usual amount of static which alerts Amuro that there are listening devices present. Amuro abruptly hangs up Ran's phone on Masumi. Meanwhile, Conan intentionally gets himself kidnapped by the primary suspect. After Ran enables calling again, Masumi calls back immediately and is very upset because she was worried something had happened to Ran. Ran tells her that Conan has been kidnapped, and details to Masumi the murder at Kogoro's agency. In order to figure out where the kidnapper is headed, Kogoro and Amuro search the apartment and decide to go to the address of one of the other suspects.
Masumi arrives at suspect's home on her motorcycle, but just misses Kogoro and the gang leaving. She hears the elevator descending and rushes back downstairs in time to follow Amuro's car. Meanwhile, the culprit has been driving around with Conan while Haibara has been directing Okiya's car towards them using the criminal tracking glasses. Okiya catches up to the kidnapper and relays what the car looks like to Kogoro. Amuro sees the suspect's car heading in the opposite direction so he quickly wheels around after it. Masumi, who has been following Amuro's car this whole time, u-turns after Amuro and continues chasing. Amuro gets in front of the suspect's car and stops it. The suspect gets out of the car holding Conan at gunpoint, but Masumi drives up onto the roof of the car. She swings her motorcycle around so that the rear wheel slams into the woman's face knocking her unconscious. With tears of relief, Masumi hugs Conan, happy he is safe. Amuro, Okiya, and Vermouth look on.
Masumi is walking with Sonoko and Ran, and Ran is talking by phone with Conan. Masumi hears Haibara's voice in the background and becomes curious. She asks the two others what Haibara is like, and Sonoko says Haibara is like a woman in a child's body.
When Ran hangs up her cellphone, the topic switches over to Amuro. Masumi says to Ran she wants to meet Amuro because she never got a really good look at him from the last case, but Sonoko thinks she wants to meet Conan, instead. Ran says Shinichi and Conan are big fans of Sherlock Holmes. Masumi thinks about that she has known that for a long time.
Suddenly, Masumi sees Scar Akai in the crowd ahead. She runs after him, but she can't catch him. Ran wonders who Masumi was chasing, but Masumi replies she thought it was someone she knew, and silently appends in her mind that it would be impossible for the man she was chasing to be the person she thinks it was.
Masumi meets Subaru Okiya at Shinichi's house and she finds him suspicious. She began to think there is a woman at Kudo's house because there are a hair elastic, lipstick in a glass and a long hair in the sink trap. After that, all of them solved a case together that is similar to a case that Shinichi Kudo's father dropped out 10 years ago. It was revealed to be a theft case. Both Subaru and Masumi had got more suspicious of Conan and the identity of Shinichi Kudo. At the end, when the criminals were knocked, she saw Ran and Conan and she thought she was a 'bad kid', after all.
She went camping when she meets Professor Agasa and Conan. The Detective Boys were lost. Masumi and Conan found the two policemen finding the corpse. After she and Conan solved the case, she and Conan rushed towards the burning cabin. Conan and the Detective Boys were talking about how they got safe. Mitsuhiko pointed the way were their savior went. Masumi then began to ask what kind of woman is their savior. She seemed to be surprised when she saw her on Mitsuhiko's cell phone.
Masumi finally meets Haibara, and Haibara has a bad feeling about her (although it could have been due to Scar Akai spying on them from behind the door just then). Later when a murder occurs on the Bell Tree Express, she and Conan investigate. Masumi takes a video recording of the suspects running so she can show it to the detective boys in order to ask them which one had the closest gait to the masked suspect from earlier, but she is intercepted first by Scar Akai in the hallway. She stops and angrily asks him who he is. Scar Akai simply replies that she hasn't changed, reveals his face to her, and refers to her by her first name, "Masumi". In her shock Masumi calls him "Shu-nii", signifying that Shuichi is Masumi's older brother. She questions Scar Akai about what happened, saying that she heard he had died. Scar Akai then tasers her unconscious, stating that he was hoping for that response. Scar Akai later is revealed to be Vermouth in disguise, explaining why he attacked Masumi.
Masumi accompanies Conan, Ran, and Sonoko to the location of Kaitou Kid's next heist: a museum where the Blush Mermaid, a gem adhered to the shell of a turtle as a last ditch effort by a an Italian actress in an accident at sea to save her turtle by encouraging someone to rescue it. Before checking out the museum, Masumi asks Ran if she saw a strange man in black when she found the hat on the Belltree Express. After the group arrives at the room where the turtle is being held in a large aquarium, Inspector Nakamori pulls Masumi's face to see if it is a mask worn by Kid. Annoyed by Nakamori's mistaken gender assumption and having her face pinched, Masumi knees him in the privates ostensibly to prove he isn't Kid. Masumi then runs off to the bathroom. Later, when Kid makes his move, Masumi is one of many caught in his trap: the rug on the floor is pulled up by strings so that it pins everyone standing on it to the front of aquarium. As soon as the rug drops, everyone sees the tank is empty except for a card left by Kid. This leaves Conan and Masumi quite dumbfounded as to how Kaitou Kid could have removed the turtle. Later, Conan reveals that Masumi is really Kaitou Kid, and he had made a critical error in his acting by assuming Masumi was a male. Kaitou Kid had locked the real Masumi bound and gagged in the men's bathroom after knocking her out with a stun gun. Upon gaining consciousness, Masumi escapes her bonds, rushes out of the bathroom, and gives a still disguised Kid a fierce kick to the face. After Kid escapes (due to Ran distracting Masumi by pointing out that everyone can see her underwear), Masumi is relieved that she at least managed to recover her hat, which she thinks is special because it somehow has the same feel as her brother Shuichi Akai's hat.
Conan, Ran, Sonoko, Kogoro and Masumi go to a live cooking show. Conan wants to ask something important to Masumi, but a murder gets in his way. While solving the case, Ran realises that Masumi and her might have met each other before, since Ran thinks of waves in the beach each time Masumi gets away. At the end of the case, Conan asks Masumi if they had met each other before. Masumi smiles and says she doesn´t know, but actually she thinks "Of course we have, but I can´t tell you until the time comes..."
After being hired by a classmate, Keiko Kitao, Masumi is investigating to see if the boyfriend of Keiko's sister has fully committed to their relationship. However, as the atmosphere is rapidly changed by the murder, Masumi and Conan start to investigate the crime scene. When Conan has finally deduced who the culprit is, he also observes Masumi making a call with someone saying "...Say, my deduction... It's not wrong, is it?". Upon solving the case, Eri states having seen Masumi talking to her brother on the phone.
At a Bowling Center with Conan, Ran, Sonoko and Kogoro, Masumi is introduced to Sonoko's boyfriend Makoto. Shortly before, Makoto mistakes Masumi for a stranger being "overly friendly" with Sonoko and tries to fight her. Masumi explains that she has been taught Jeet Kune Do by her older brother, she also reveals that besides her assumingly dead brother, she also has a second-oldest brother. Furthermore, Masumi explains to Conan that her brother also advises her on cases by phone. After successfully investigating the crime scene with Conan, Masumi steps aside with her smartphone and types in the message "It seems like he's also arrived at the truth... But whether or not our deductions are the same - lately I've been losing confidence in that regard...". When the recipient writes back "Who is he? I'd like an explanation!", Masumi takes a picture with her smartphone. However, the recipient's answer, "If it's him, there's no problem." reveals that he is familiar with Conan. It is heavily implied that it is the same person Conan saw Masumi making a call with in File 857.
Masumi takes a request from her middle brother to consult in his place about a case involving some of his high school classmates who are now 28-29 years old. On the way to a cabin in the woods, Masumi tells Conan and the gang more about her family history and timeline. She reveals that she and her brothers each have different family names for various reasons, one of which is the death of her father. The case takes a dark turn when one of the classmates is found murdered in a bathtub of tomatoes. With the help of the Nagano police, Conan and Masumi manage to solve the case. Later, Masumi asks Conan to find her cellphone in the kitchen by calling it with his. He does so and Conan notices the call background screen is a child who looks like Masumi with eye bags similar to those of the Akai family members. Masumi mentions having a younger sister earlier on (Episode 754), so Conan suspects Masumi was intentionally trying to show him the child for some reason.
On the way home from school, Ran and Sonoko decide to visit Masumi's hotel (which is different from the other one she has been staying at earlier). Masumi claims she had a meeting with her supposedly-hard-to-reach middle brother planned, so she texts him to reschedule. Conan seems to notice this contradiction. At the hotel, Conan tries to peek in Masumi's bedroom, but Masumi wards him off by embarrassing him. Masumi also asks Conan is she reminds him of someone he met in the past, but Conan draws a blank. A murder interrupts the meeting. While Conan is investigating, he notices the middle-school aged child from Masumi's cellphone picture in the gathered crowd. Later, Conan and the gang return to Masumi's room, and Conan hides his glasses earpiece microphone to spy on the apartment. It is quickly found and destroyed by Masumi and the child after Conan departs with Ran and Sonoko. Masumi asks the child is she is beginning to like him, but the child responds that she is still long way from trusting him. The child asks Masumi to tell Conan she is her little sister from outside the territory if he asks about her. Masumi doesn't mention that she showed Conan the child's picture.
Masumi and Mary has moved into another hotel, where a murder takes place next door.
Masumi intentionally puts on a bathing suit similar to the one that she had worn in the past to try to jog Conan's memory of where they met. A case occurs, which involved the method of counting fingers in different countries. Masumi seems to count the same way that is used in the UK, but seems to think that it is the way it is done in the US. As Conan corrects her, she seems confused. Conan thinks back on all of the times that Masumi has done things that seem to imply that she was in the UK rather than the US and he finally remembers the events of 10 years ago by repeating イギリス (Igirisu / Britain) in is head.
Masumi and Sonoko meets up with Ran in a café to discuss details of the school field trip to Kyoto.
 Non-Canon Plot Overview
 Movie 18: Dimensional Sniper
Sera appeared in this movie as an investigator of the person who had been shot in the Bell Tower. She and Conan helped in chasing the culprit and afterwards was shot by the culprit after saving Conan.
 Plot Exposition
 Hints that Masumi was Shuichi Akai's sister
- Masumi has bags under her eyes identical to Shuichi Akai's.
- Masumi Sera's name is also incredibly similar to Mobile Suit Gundam character Sayla Mass (セイラ・マス, Seira Masu). Shuichi's name is derived from Sayla Mass's older brother's name, Char Aznable.
- Conan said he has a feeling he had met her before. "Somehow I feel like we've met somewhere before, it might be that person resembles someone I know, that's why the feeling that we've met before is on my mind..."
- Andre Camel and most likely James Black seem to recognize her from somewhere. On another interesting note, James was the first to recognize that Masumi was a girl. Everyone else thought that she was a guy when they first saw her. Since James was Shuichi's boss, he would most likely know that Shuichi has a younger sister and what she would look like.
- Masumi lived in Japan until three years ago when her family moved to America. This matches with the time when Shuichi was infiltrating the Black Organization. The family's move to America could be the FBI's attempt to protect them should something go wrong with Shuichi's mission.
- In Chapter 801, Masumi chased after Scar Akai who appeared while she was walking with Ran in front of the Mouri Detective Agency. Although, Scar Akai hid before she could find him, she told Ran that she had just seen "someone she knew".
- In Chapter 859, Masumi, when being asked who taught her Jeet Kune Do, answers that her older brother did. Consequently, Conan asks Sera: "But, didn't you say your older brother was dead?" This leads to Masumi remarking "Yeah... That's what I heard." also further supporting the theory that Masumi is in Japan to investigate her brother's death.
 Hints that Masumi was not Bourbon
- In Chapter 801, Masumi chased after Scar Akai who appeared while she was walking with Ran in front of the Mouri Detective Agency. Although, Scar Akai hid before she could find him, she told Ran that she had just seen "someone she knew". She then thinks there is "no way it was possible" regarding the man she saw, which would make sense if she thought Shuichi was dead. This implied she wasn't Bourbon, since Bourbon believes he is the only one who can kill Shuichi, implying that Gin might have failed to do so. Hence Bourbon wouldn't think that it was impossible to meet Shuichi again in the street.
 Relationships analysis
 Friends & Family
 Shuichi Akai
Shuichi Akai is Masumi's older brother. She didn't get to meet him until she was six-seven years old, because Shuichi went to study abroad before Masumi was born. At first meeting she was very shy, but she did make some pranks in an attempt to make him smile. Masumi refers to Shuichi as "Shu-nii", implying that they were close. Masumi seems to miss him after his supposed death. In the Blush Mermaid Heist, Masumi is shown to be fond of her fedora as she believes it has the same "feel" as Shuichi's old hats. Shuichi sent Masumi Jeet-Kune-Do training tapes while she was in elementary school. She watched these so many times while practicing that she wore them out. She describes her eldest brother as strong in contrast to her second - oldest brother.
 Conan Edogawa
Masumi is interested in Conan's abilities as a detective and has been gathering information on him and his friends. She appears to be certain that Conan is Shinichi Kudo. Despite her initial suspicious presentation, Conan felt like she wasn't a bad person and so didn't mistrust her. Conan at several points questions her if they've met before, but she denies this, once secretly thinking, "Now's not the time". The period in which such an encounter could have taken place is initially hinted to be somewhere before the three-year span of Masumi's sojourn in the United States, when she was in her preteen years.
It is later shown that she had met Conan/Shinichi ten years ago, when the Akai family had gathered on an undisclosed beach in Japan prior to Shuichi Akai joining the FBI. By chance, Shinichi and Ran had also vacationed there, and they all ended up as witnesses and investigators in a gone-awry flight attempt from a robbery. When Shinichi managed to make Shuichi laugh (something Masumi had miserably failed to achieve) with his intelligence, observation skills and some unintended jokes, Masumi, in her admiration for Shinichi, began to call him "wizard". It is quite possible that this meeting inspired Masumi to become a detective herself.
If Masumi really lived in England, instead of America, then it's possible that she saw the tennis match from the London case on TV and recognized Conan as Shinichi based on his proclamation as 'Holmes' apprentice'.
On several occasions, such as the dramatic conclusion of the Online Client Case, Masumi has displayed an intensely affectionate air towards Conan which somewhat transcends a mere "big sister" relationship. In fact, it is hinted during the Romance Novelist murder and in the movie Dimensional Sniper that she may actually be entertaining a crush on Shinichi/Conan and hopes of initiating a closer relationship with him. However, the actual level of her feelings for him is yet to be publicly revealed.
 Ai Haibara
Masumi has been interested in meeting Ai Haibara for yet unrevealed reasons and has been secretly gathering information on her. She also seemed to recognize Shiho Miyano in the video of her rescuing the Detective Boys. Haibara in turn feels uneasy around Masumi, especially in close contact situations though arguably it could also be due to Scar Akai's presence near Masumi. The reason behind her interest might be due to Haibara's resemblance with Mary.
 Ran Mouri
Since enrolling at Teitan High, Masumi and Ran have become friends and often walk home from school together. Masumi has also declared Ran as "her type" when they first met as a sign of liking, though this ultimately led Sonoko, Conan and Ran herself to mistake Masumi for a boy.
At one point, Ran recalls having met Masumi before in the past, hearing the sound of "rippling waves" when the she sees the latter leaving, "as if some sort of magic were at work". It is revealed in a later story that she and Masumi had actually met 10 years before, when they were both still children, on a beach, where by happenstance she, Shinichi and the Akai family inadvertently became embroiled in the aftermath of a crime (see Conan Edogawa, above).
 Sonoko Suzuki
Since enrolling at Teitan High, Masumi and Sonoko have become friends and often walk home from school together, with Sonoko describing Masumi as a popular girl who is "cheery, sociable, boyish and cute" and on top of that, a "Jeet Kune Do using detective", though she also teasingly remarks that the only thing "against Sera" is her flat chest.
 Akai family's middle brother
Masumi appears to have a good relationship with her second-older brother and often consults him regarding information or deductions about the cases she faced, and also has a high regard of her brother's intellect, even considering the already sharp Shuichi as "strong" in contrast to her second older-brother.
 Tsutomi Akai
Masumi's father died before she was born, so she never knew him. But he refer to him as 'Papa'
 Mary Sera
Mary seems very mature and cold while talking to Masumi. She also treats her more like a coworker than her daughter, as she always advises her what to do and switch hotels if any intel about Mary is leaked.She is also somehow stubborn as she declined Masumi's trust in Conan despite the latter's motive and pursuit of justice are geniune.
 Black Organization
 Rei Furuya
Rei first saw Masumi in Detectives Nocturne case and seemed to recognise her. They formally met in chapter 936 (Girls Band) at Café Poirot. Masumi felt like having met him and even asked him directly about that, but Rei said that was the first time they met. When Masumi talked about a friend of her brother who taught her play the guitar, Rei also seemed to know about that incident. In Masumi's flashback of that friend, a man who looked very much like Rei appeared, and Masumi once again wondered about it, to which Amuro replied that she took the wrong person.
 Masumi met Shinichi and Ran when she was younger and knows Conan is Shinichi
- Masumi knew Conan and Ran's identities before they introduced themselves. She also knew that Conan is a detective.
- Masumi seems to know that Conan is the brains behind Sleeping Kogoro. Conan seems to think that he may have met Masumi before or that she resembles someone that he knows. He believes that she got the deduction of a case wrong just so that he would reveal himself. 
- Conan realizes he met Masumi before because he finds her snaggletoothed smile familiar,
- Masumi admits that she has met Conan before, but she can´t tell him until "the time" comes.
- Ran has met Masumi as well because Masumi's figure as she runs away reminds her of "sounds of rippling waves, as if some sort of magic were at work."
- Masumi, asks Conan if he once met a girl "a long time ago and could never forget [her]" and gets annoyed when he says he can't recall someone like that.
- Ran has a flashback to when she saw a younger Masumi, who is wearing a bathing suit, say, "You are a wizard, right?". Ran also feels that she has met Mary.
- The meeting occurred 10 years ago, as mentioned by Mary.
- Masumi puts on a swimsuit similar to the one in Ran's flashback in order to jog Conan's memory, which results in him remembering her in that bathing suit as well, along as three other people, assumed to be her relatives. 
In Chapter 771, it is revealed that she also knows Professor Agasa, although she calls him "Professor what's his name". Although this could be explained away as her talking to Conan off screen and her just not remembering Agasa's name.
 Identity of Masumi's middle brother
 The Wizard
In a PS, Masumi's middle brother asks if she "has already met the Wizard?" Masumi's thought reply is "You could say so..." Later, Masumi "thinks aloud" that her reason for returning to Japan is to meet the Wizard once more. The identity of the Wizard is revealed in File 974 to be Shinichi.
 Shinichi Kudo
Tellingly, Masumi turns towards Conan when thinking of the answer "You could say so". At this point Masumi seems to know Conan is Shinichi. If Shinichi was nicknamed "The Wizard" by Masumi and/or her brother because of what happened when he and Masumi met in the past, then the response is appropriate since she could only sort of meet with Shinichi, because Shinichi shrunk into Conan. It's possible that the event where Shinichi earned the nickname "The Wizard" was Shinichi and Ran's meeting with Masumi 10 years ago. When trying to remember Masumi, Ran specifically mentions "sounds of rippling waves, as if some sort of magic were at work." A "magical" incident, if it was Shinichi's doing, might have earned him the nickname. Ran has a flashback of a young Masumi saying "You are a wizard, right?". Conan seems to have remembered meeting Masumi 10 years ago and is shown as a young Shinichi standing in front of a large wave.
 Someone else
At this point it is unlikely that the Wizard is anyone else. There is evidence that Masumi nicknamed the person who she calls Wizard, at a point in the past while Ran was nearby. If Ran was nearby, then this would have to have happened when they first met 10 years ago, meaning that the person must be someone who existed back then. The topic of the Wizard came up during a text conversation about Conan between Masumi and her middle brother, and her response to if she had met the Wizard again was "You could say so", which is more than likely implying that she is referring to Conan, and therefore Shinichi.
 Masumi learned about Haibara from Shuichi's picture
Masumi initially had an interest in Haibara. This is strange because Haibara didn't exist prior to Shiho shrinking. The knowledge of Shiho should have been secret to her as well, because Shuichi Akai's infiltration of the Black Organization was a secret. If Masumi doesn't even know the details of her brother's death, why should she know about Shiho? Masumi may recognize Haibara from pictures of Conan and Haibara that Shuichi took back during the Vermouth arc. It is standard procedure in the US to send the personal belongings of the dead back to their families. If Shuichi mixed these pictures in with his own things when he took them out of his truck before meeting with Kir, it's possible they were overlooked when the FBI sent Shuichi 's things to his family. If Masumi was interested in finding out how and why Shuichi died, she would begin by researching the people in those pictures and those connected with them in hopes of finding clues.
 Character popularity
- In honor of the release of the 800th manga chapter, Shonen Sunday held a popularity poll/contest containing 91 Detective Conan characters to choose from. Masumi placed 9th overall with 292 votes.
- Masumi ranked 10th in the Digest Book 50+ poll "Best Detective Conan characters", with 107 votes.
- Masumi ranked 5th in the Digest Book 60+ poll "Cutest Detective Conan characters", with 135 votes.
- Masumi ranked 10th in the Digest Book 70+ poll "Characters you want to go on a date with", with 106 votes.
- Masumi ranked 11th in the Digest Book 80+ poll "Character you want to marry", with 281 votes.
 Name origin
Masumi Sera's (世良・真純 Sera Masumi) name comes from the Mobile Suit Gundam character Sayla Mass (セイラ・マス Seira Masu). The kanji for Masumi's surname mean 'good world'. The kanji for her first name, Masumi, mean 'true' and either 'pure' or 'net.'
|“||Deletion. For data at least ... is an easy task to accomplish.||„|
— Masumi, on deleting a picture of Haibara from her computer, File 777 pg 16
|“||I guess I'm a bad kid after all...||„|
— Masumi, while crying, File 814 pg 16
- Masumi is based on Natsuki Koshimizu, a tomboy detective girl turned criminal who made her first appearance in the Detective Koshien Case. Since Natsuki had proven highly popular, but Aoyama couldn't recycle her as a protagonist, the character of Masumi was created instead.
- When she was young she liked to read the "Night Baron" series, so she is fan of Yusaku Kudo.
- Her catchphrase, "Case Closed" (said in English), is likely a reference to the English-language name of Detective Conan.
- Masumi owns an Artesia XT400.
- In File 859, Masumi reveals that she has a second-older brother and that her oldest brother taught her Jeet-Kune-Do.
- Masumi speaks Queen's English.
 In other languages
|Language||Given Name||Family Name|
|Japanese||真純 Masumi||世良 Sera|
|Arabic||ماسومي Māsūmi||سيرا Sēra|
|Flag of Mexico American Spanish||Masumi||Sera|
|Flag of Brazil Brazilian Portuguese||Masumi||Sera|
|Korean||세라 Sera||양 Yang|
|Thai||มาสึมิ Mās̄ụ-mi||เซระ Sera|
 See also
- ^ Noriko Hidaka (2012-02-01). "新しいお仕事". combination Co.Ltd.. http://combination.jp/blog/2012/02/post-383.html. Retrieved on 2012-02-01.
- ^ Manga Volume 73, File 9, Page 3, "Let's hear your brilliant deduction!"
- ^ a b The Japanese pronoun used is gender neutral and can refer to either males or females.
- ^ Manga Volume 73, File 7, pg 3: "A Detective Just Like You, Little Boy"
- ^ a b c File 930 (Volume 88)
- ^ a b File 771 (Volume 73)
- ^ a b c Movie 18: Dimensional Sniper
- ^ a b Episode 690
- ^ File 778
- ^ File 820 (Volume 78)
- ^ a b c d File 953: As If Connecting with a Demon in the Darkness (Volume 90)
- ^ a b c File 972 (Volume 92)
- ^ a b c File 936
- ^ a b File 938: The Crime in the Blind Spot (Volume 89)
- ^ a b File 859: Jeet Kune Do vs. Karate (Volume 81)
- ^ a b File 954: Sanction of the Betrayal (Volume 90)
- ^ File:AChint8-06-2014_4.JPG (Sera-chan calls him Kichi-nii)
- ^ File 929 (Volume 88)
- ^ File 905 (Volume 86)
- ^ a b c File 828 (Volume 78)
- ^ a b File 937
- ^ a b File 858: A Problematic Deduction (Volume 81)
- ^ Volume 78, File 6
- ^ a b The Jet-Black Mystery Train
- ^ File 952: In the Suspicious Next Room (Volume 90)
- ^ Manga Volume 73, File 9, Page 3, "Let's hear your brilliant deduction!"
- ^ Volume 73, File 11, page 13, "Possible Sniping." Shinichi then begins to present his deductions over the phone and Masumi wonders how he will manage to resolve this situation without bloodshed.
- ^ Manga Volume 78, File 4 (821), pg 16: "Mystery Train (Junction)"
- ^ Manga Volume 78, File 6 (823), pg 4: "Mystery Train (Releasing Smoke)"
- ^ Manga Chapter 771: Let's Hear Your Brilliant Deduction! p.11
- ^ Manga Volume 83, File 4 (876), pg 2: "Romance Novelist"
- ^ Manga Volume 81, File 9 (859): pgs 6-7: "Jeet Kune Do vs. Karate"
- ^ Manga Volume 83, File 2 (874), pg 7-8: "Red Past"
- ^ a b Manga Volume 86, File 1 (905): "The Truth Rises to the Surface"
- ^ a b Manga Volume 92, File 2-4 (972-974): "A Chance Meeting at the Beach"
- ^ Manga Chapter 800: Online Client Case - "When Objects Collide"; Anime Episode 674: Detectives' Nocturne - "Bourbon"
- ^ Volume 73, File 6 (768)
- ^ Volume 73, File 9 (771)
- ^ Manga Volume 80, File 6 (845), pg 16: "Our Territory"
- ^ Manga Volume 80, File 7 (846), pg 16: "The Magic Lock"
- ^ a b Manga Volume 80, File 7 (846), pg 4: "The Magic Lock"
- ^ Manga Volume 83, File 4 (876), pg 11: "The Romance Novelist"
- ^ Manga Volume 86, File 1 (905)
- ^ Manga Volume 90, File 5 (953)
- ^ Manga Volume 91, File 11 (969)
- ^ Manga Volume 81, File 11 (861), pg 15-16: "Just like Magic"
- ^ Manga Volume 83, File 2 (874), pg 8: "The red past"
- ^ Manga Volume 86, File 1 (905)
- ^ Manga Volume 92, File 2 (971)
- ^ "Shonen magazine detective conan official poll results published [magazine pic"]. eva. 2012-02-28. http://forums.dctp.ws/viewtopic.php?f=4&t=8024. Retrieved on 2012-02-29.
- ^ Sherry's soliloquy (2012-06-17), Gosho was referring to the revelation that Masumi is Shuichi's sister (Manga File 821): やっぱりアルテイシアだったのね・・・ (So it was Artesia…). Note that "Artesia" is another name of Sayla Mass.
- ^ Shonen Sunday #33
- ^ File:Postcard2015 1.jpg