|Japanese name:|| 大岡 紅葉 |
|First appearance:|| Manga: File 962 |
Anime: Episode 874
|Appearances:|| Chapters: 9|
|Japanese voice:||Satsuki Yukino|
Momiji Ooka is a second-year student from Kyoto High School and a champion of Hyakunin Isshu karuta. Her family is likely wealthy since she has a butler. Momiji claims Heiji Hattori 'proposed her when they were little' and thus believes that they will be romantically involved in the future.
She was once part of an elite karuta association called Nagoro-kai. She was the greatest student of the group's founder, Nagoro Shikao. However, after the group was disbanded she joined another association called the Satsuki-kai.
Momiji appears to be an extremely competent detective, as she saw through a trick merely based on a sound she heard in a phone call with her butler, Muga Iori, before Conan, Heiji or Bourbon did. Later, Muga says that her deduction was great as usual, implying that she regularly solves cases and also says that Heiji's great deductive skill was to be expected from the person that Momiji chose as her partner.
Momiji is involved in the plot of movie 21 which will center around Heiji and Kazuha's romance. She is shown crying in the movie artwork. The trailer of the movie shows her in an uta-karuta tournament and introducing herself as "Heiji's fiancé", plus there's a picture of her and Heiji's younger selves making a pinky swear.
Momiji has a close personal interest in Heiji's cases as he makes the news. For some reason, she believes Heiji will be her future husband, despite his feelings for Kazuha. The trailers for the 21st movie imply that she and Heiji did meet as children and apparently made a promise.
Momiji is also extremely smart, especially in regards to catching details that others miss. When Muga Iori informed her via phone some details about a case Heiji was working, Momiji actually caught other signals that Muga himself had missed and used them to reach a correct deduction that would greatly help Conan and Heiji. Muga also implies that Momiji engages in her own detective work at times, as she is no stranger to making such deductions.
Momiji seems to be very girlish and fond of taking some degree of care in her appearance. She had pierced ears and small earrings, and her nails are seen painted in intricate patterns. Momiji also has a notably larger bust size than other girls in the series, flustering Heiji in their first meeting in Movie 21, making flat-chested Masumi jealous and baffled when she first sees Momiji, and leading Okita to simply referring to Momiji as "Boobs" in a conversation with Ran.
Finally, Momiji is a champion in the famous card game Hyakunin Isshu Karuta, a game that Kazuha is also proficient in. The movie plot takes place as both she and Kazuha are getting ready for a karuta tournament.
 Plot Overview
 Non-Canon Plot Overview
 Movie 21: The Crimson Love Letter
 Heiji Hattori
Momiji and Hattori made a promise years ago which she still remembers which was revealed to be that Heiji proposed to her. She immediately recognized him, but Heiji at first didn't. She has a love interest for Heiji and even calls him her "future husband". Because of this, Momiji and Kazuha consider one another as rivals and their interactions are laced with one or another degree of passive-aggression.
 Muga Iori
Iori is Momiji's butler and loyal servant. She values that he approves of Heiji as her future husband.
 Soshi Okita
Momiji and Okita are classmates. While talking to Ran, Momiji is annoyed at the mere mention of Okita, though she is willing to deliver a message from Ran to him. When he later comes over to the crime scene with some kendo buddies to hunt down tengus, Momiji only has sarcastic comments and further annoyance to offer. In turn, Okita doesn't want Momiji to learn of the girl he has a crush on, fearing he would never hear the end of it if she heard of his crush. Somewhat rudely, Okita only refers to Momiji as "Boobs" in a conversation with Ran, in reference to her overly large breasts.
 Ran Mori
 Manga vs. Anime
In the movie 21, Ran and Momiji met in Osaka, while Ran says in the manga she met Momiji in Kyoto. Then, in the manga, Ran meet Momiji some time off-screen, similar to how Ran already knew Naeko Miike in File 928 without having met her previously on-screen. Inspector Shiratori and Conan first met in the manga off-screen as well, with them having originally met in the movies, which are not canon and Gosho Aoyama simply omitting their first meeting in the manga doesn't make the movies canon either.
In the manga, Files 033-035 is the first and only time when Kogoro goes in train to Kyoto for a friend wedding. Ran came along to see Kyoto for the first time, and brought Conan rather than leave him alone in Tokyo.
In The Missing Sweets in the Old Shop, not based on the manga and pre-story of the movie 17, Private Eye in the Distant Sea, Sonoko goes to Kyoto with Ran, while in the manga she doesn't know Momiji yet.
 Name origin
Her name Momiji means "red leaves" and her surname Ooka means "large hill".
 In other languages
|Language||Given Name||Family Name|
|Japanese||紅葉 Momiji||大岡 Ōoka|