Kamui Uehara is a major character in The Silver Case who is also mentioned in Flower, Sun, and Rain. Kamui is set up as the main antagonist of The Silver Case, but this is questioned very shortly; as the game progresses, Kamui's role mainly becomes that of a figure and symbol in the culture of Ward 24.
The original incarnation of Kamui Uehara, known as the Format Kamui, is shrouded in mystery. KamuiNet paints a picture of how he is seen by the populace: as a heroic assassin who killed corrupt government executives and other criminals who were otherwise untouched by the formal legal system. KamuiNet lists five major crimes Kamui committed between 1975 and 1979, every time in the middle of winter. In 1975, Kamui was 16. The website does not state if these were Kamui's first crimes, and describes the list as merely an "estimated criminal record". The people Kamui supposedly killed during this time were Makoto Ishihara, Yukio Hata, five students and Toshiki Sato. These killings culminated in the event known as the Silver Case.
According to KamuiNet, Kamui killed Ginji Nakane, the chairman of the TRO/CCO confederation, by stabbing him outside the front door of the TV Tower. After this, Kamui was immediately arrested. This is considered to be the public face of the events of the Silver Case. However, according to Tetsugoro Kusabi and other characters, this is only one version of the event, which is extrapolated from the name Kamui Uehara, the only part of the case to be reported publicly. Kusabi and other sources describe Format Kamui as a hitman who worked for the FSO party and a perfect citizen who was both extremely obedient and able to commit brutal murders. Sent by the FSO, Kamui did more than just kill Nakane, he also killed all of the elderly leaders of the TRO/CCO alliance, after which he was killed by Kusabi.
Apparently, Kamui did not have any birth records with the government. His origins are never made clear, but Kusabi considers the idea that Kamui was possibly not even human.
Even this information, however, is contradicted by Kusabi himself not too long after. He claims that Kamui was actually completely innocent, and was killed by the elders to claim his Silver Eyes.
The Shelter Kids Policy was later implemented by Uminosuke Hachisuka in the 1980s. Children raised through the Shelter Kids Policy were inserted into key positions in Ward 24. Possibly due to Format Kamui's Silver Eyes, Kamui's personality could be inserted into any males who grew up as shelter kids. This meant that the government could repeatedly activate Kamui, which they could use for assassinations (the political factions) or to make a statement to society (Nezu, who used Kamui as the equivalent of an 'in-game event'). Because the fact that the Format Kamui was killed was never made public, the people believed these Kamuis to all be the same one. Publicly, Kamui was sent to the psych ward of IMM Hospital in 1984.
The circumstances regarding the emergence of Kamui's personality are not detailed, but they involve the crime ring TRUMP, Kamui's "bodyguards", going to the Triangle Towers. Prior to the events of case#1:decoyman, the current Kamui enters counseling by Yuriko Sonoda.
In case#1:decoyman, it is initially believed that Kamui Uehara is killing young women in Ward 24, as they are turning up dead and Kamui has disappeared from the hospital. However, it is eventually discovered by the Heinous Crimes Unit that the killings are being carried out by Ayame Shimohira, who has tied up Kamui in the art studio Gladiolus. Kamui is found to be incapable of speaking or taking care of himself, let alone killing, and he is brought back to the 24 Precinct. Morichika Nakategawa investigates and finds information from the FSO that indicates that Kamui was born in the Shelter. (As described above, this is only part of the truth; likely the reason that Kamui was incapable of much was due to being deactivated by the government.) It was previously believed that Kamui grew up in Cape Kamui, a cape in Hokkaido.
Kamui remains dormant for much of the rest of the game. Despite this, several other characters turn their interests to Kamui; Tokio Morishima takes on a job to research and write about him, and people such as Kaiji Enzawa and the Method Tank proclaim interests in Kamui, who becomes a savior figure in the society of Ward 24. He gains an entire fansite in the form of KamuiNet which features information on his past crimes and a chatroom for fans to discuss him. This all culminates in November of 1999, in case#5:lifecut, when Kamui is reactivated, escapes from the hospital and begins to kill government officials once again. He gains more popularity than ever before, especially with the youth, and this counter-cultural movement gains enough traction to even be the subject of a short TV special documentary. The primary justification for this from the youth is the belief that Kamui embodies purpose and perfection beyond what people are able to accomplish in modern society, regardless of the fact that his purpose is to commit murder.
At the end of November, the Heinous Crimes Unit hunts down Kamui at the IEDU Building. They chase him to the roof, on top of which he is shot to death by several snipers. Akira, now having been instructed to go after TRUMP, finds a lead that takes him to the Shelter in which they have been killed. While underground, both Sakura Natsume and Kusabi tell Akira that he is a shelter kid who has been called down there to become the next Kamui. Despite this implication, Kusabi later changes his mind and says that it's actually up to Akira whether he becomes Kamui or not.
In report*5:HIKARI, Uminosuke talks to Tokio and reaffirms that Kamui is transferring into Akira. Seemingly believing that Kamui has become too dangerous to control, Uminosuke tries to convince Tokio to kill Akira to stop Kamui from transferring, claiming that the action will remove Tokio's lingering consciousnesses. Even this is denied, however, as Tokio refuses to kill Akira.
At the very end of case#!:tamura, after the credits, Sakura and Michiru Kosaka imply that a new Kamui has killed Uminosuke. This confuses Kusabi, who questions who the hell Akira really is, but his questions are only answered by a "TO BE CONTINUED...?" message. This may have just been another copycat, however; one theory is that it is Tokio, acquiring his Silver Eye.