Seiji Asoh

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Seiji Asoh

Seiji Asoh Before.jpg

Japanese name: 麻生成実 (Asō Seiji)
浅井成実 (Asai Seiji/Narumi)
English name: Nadia Adams (real name Simon Austin)
Age: 26 (deceased)
Gender: Male (female in disguise)
Date of birth: unknown
Relatives: Keiji Asoh (father, deceased)
Mrs. Asoh (deceased)
Ms. Asoh (younger sister, deceased)
Occupation: Tsukikage Island doctor
Aliases: Narumi Asai (fake identity)
First appearance: Manga: File 62
Anime: Episode 11
Appearances: Chapters: 7
Episodes: 3
Specials: 1
Cases solved: 0
Keyhole number: N/A
Japanese voice: Ai Orikasa

Seiji Asoh (麻生成実 Asō Seiji?) is a character in the manga and anime franchise Detective Conan.


Seiji Asoh is a serial killer from Tokyo, where he's known as Narumi Asai (浅井成実 Asai Narumi?), a female doctor from Tsukikage Island who liked to heal children, but he commits suicide after having been uncovered for the serial murders he had done. His father was Keiji Asoh, a famous musician. One night twelve years ago Keiji along with his wife and his daughter were killed in a fire. Everyone assumed that Keiji had murdered his family and committed suicide. Seiji wasn't killed, because he had been in a hospital in Tokyo. Later he got adopted.


Plot overview[edit]

In the second murder, they found that he had been dead for only a few minutes but when Conan fell on the code of blood, it didn't smear when it takes 25-30 minutes for human blood to dry. It was just a trick that the killer used to manipulate the time of death of the victim. Upon looking at the pictures, there was a button that was lighted near Kuroiwa's neck. But after the body was moved, the light was turned off. This was actually the reverse button. While the police weren't looking, the killer turned off the light. The killer used the reverse side (the blank side that didn't have the song), which played for over 30 min and then it reversed. That was when the 5 minutes and 30 seconds of gap played before the music started.

In the third murder, the killer didn't have the time to put a chair or desk at Nishimoto's feet because he had to escape in time. The killer was probably male because the murders required a lot of physical strength.

The purpose of drowning Kawashima was to send the forensic examiner back to Tokyo, because it was impossible to do an autopsy on the island. The tape in the second murder was a setup so the killer could create an alibi.

Conan deduced that the killer was Narumi Asai and that she was, in fact, Asoh's aforementioned son, Seiji Asoh. Asai was probably the surname of the family that adopted him. After graduation, he came to the island as a female doctor. The pronunciation of his name was not written on his diploma, nor the medical license, because if they checked his history, they would have found out that he was a man: the kanji forming Asoh's name could be read as either "Seiji" (a male-only name) or "Narumi" (a female-only name): coupled with Asoh's feminine features and rather girlish voice, it let him masquerade as a female doctor rather well, plus falsifying the times of death and manipulating the crime scenes. He also stayed all night so that they'd make him last for questioning, keeping the "disguise" intact.

As for Murasawa, he was an admirer of the late Asoh and he was the one who kept the donated piano in tune just like that night.

As Conan-through-Kogoro explained all of this, suddenly the police came in and said that Seiji/Narumi had escaped. While they were looking for him, the community center building suddenly went up in flames: it turns out Seiji, who had realized that he had been found out, locked himself inside and set it on fire, intending to die like his father.

Conan, carrying Asoh's last music sheets with his message for the then-young Seiji, managed to slip in and told Seiji, who was sitting at the piano, to keep on living. Seiji confirmed that he was the young boy who escaped his family's murder, plus everything that Conan-through-Kogoro had already said (explained below in "Motive"). When Seiji was done, Conan insisted that he should escape and live; Seiji refused, however, saying that he was already too bloodstained. Then, he grabbed Conan and threw him through the window, saving his life. Afterwards, he played one last music code message in the burning flames: "Thank you, little detective."

Seiji's motive dated back when his father, the pianist Keiji Asoh, and his family was murdered. Kawashima, Nishimoto, Kuroiwa, and Kameyama used Asoh's international concerts as a front for their international drug trade. When Asoh stated that he wouldn't cooperate any longer, they got scared that their secret might be exposed, so they locked the family in their home and set it on fire. This was all written in the sheet music that he left behind in the safe as his confession to his remaining son. Seiji was hospitalized in Tokyo at the time of the murder, and later was adopted by a friend of the Asoh family.

Seiji went back to the island, under his "Narumi" disguise, because he never believed that "Keiji Asoh killed his family and himself" version and wanted to find out the truth. As said above, when he told Kameyama that he was Asoh's son, the late mayor was terrified and told him everything an then had a fatal heart attack. Seiji played the Moonlight Sonata that his father loved so much upon seeing the mayor dead, and ultimately that gave him the idea of taking justice in his own hands.

After Seiji's death and the end of the case, Conan and Ran talked about him. They wondered why did Seiji summon Kogoro when he knew how risky that would be for his plan, and Conan speculated that it wasn't just a challenge - that deep down, Seiji wanted Kogoro to stop him.


Seiji's death left an impression on Conan, who might feel that he is no more different than a murderer for driving Seiji to suicide with his deduction and didn't manage save him.


He's very nice towards other people, especially children. He's also the first Tsukikage person Conan, Ran, and Kogoro meet.

Different looks[edit]

TV Special 6


  • In the Italian dub his real identity is Yoko Asoh, Keiji Asoh's elder daughter and the deceased Seiji Asoh's older sister.

See also[edit]

Minor Characters
Family & Friends Fusae CampbellMidori MegureAyako SuzukiMisae YamamuraKazumi TsukamotoAsami TsuburayaGenji KojimaCoeurHiroshi YagisawaManami YagisawaTamanosuke ItoMegumi ItoRenge KataokaSayo OhashiMidori KuriyamaChipmunkKatsumasa OguraTaiiGoroLupin (dog)Mrs. TsuburayaMrs. SatoIsokichi KamoiYuzo TomizawaHina WadaYujiro TamakiIchiro TamakiMichiko Yoshikawa
Tokyo Metropolitan Police District Officer TomeJinpei MatsudaWataru DateInspector MomoseMiss TomeParamedic SakaiMasayoshi SatoOfficer NumataTsujimura
Schools Ryujiro UematsuMaria HigashioChiharu MatsubaraNatsuko ShibuyaToya
Others Soshi OkitaSamizu KichiemonHikaru YasumotoChikara KatsumataWaitressTakeshi OnimaruSodesakiSatoru Maeda
Tokyo Supreme Court Reiko KujoSasakiPresiding judge
Medias Naomichi MugikuraKoji YatsukawaMikihiko KamisuwaShimizuKaoru KodaMiyuki TabetaYumi Hikita
Case Aquaintances Tohei BenzakiSeiji AsohKyosuke HagaNatsuki KoshimizuJunya TokitsuMinerva GlassReiko AkibaRokumichi Hado
Hospital Kazumi NakayamaKeiko Okita
Related Lists List of minor recurring anime charactersList of minor recurring manga charactersList of minor recurring movie charactersList of notable case characters