For an outline of the characters and their factions, it may also be helpful to view the manual.
It should probably go without saying, but due to the heavy focus on a mystery storyline, there will naturally be some unavoidable spoilers in these profiles, especially in the "major antagonists" section.
Sumio KodaiOne of the younger members of the HCU. Graduated from Central. A serious man when it comes to work, he doesn't get involved in division drama.
- Dark and Troubled Past: He and his friends were disabled, and their other friend killed, in a tragic event when they were children; all his actions since have gone towards getting revenge.
- Decoy Protagonist: He's always listed first in character introductions (like in the opening or on the website), and looks the most like a cool 'hero' character. But you play as someone else. Then Sumio gets arrested midway through the game, after his involvement in #3: parade.
- Hidden Depths: He comes across as the most level-headed and normal member of the team, but he's actually deeply troubled and biding his time to enact revenge on the man whose actions lead to his disability and the death of his friend.
- Hiding the Handicap: Learned lipreading and bribed and cheated his way past the police tests in order to hide the fact that he's deaf.
- The Plan: As the mastermind of the Mikumo Boys, he created the plan to take down the Yukimura Group.
- Red Oni, Blue Oni: The Blue (good cop) to Kusabi's Red (bad cop).
Tetsugoro KusabiSumio's partner. A veteran agent who arrested Kamui during the incident known as "The Silver Case". Impolite, but very skilled.
- AM/FM Characterization: Played With. In Lunatics, Kusabi's listening to a mellow piano piece on his car radio. He doesn't like it. So he changes the radio station and complains that the radio plays "nothing but shit".
- Cool Old Guy: He acts abrasive, but he's really this at heart.
- Jerkass: Especially comes off as this early on, such as in Decoyman where he berates Chizuru over very little.
- Jerk with a Heart of Gold: By the end of the game, though, it becomes clear that he's a good person who cares for his friends deep down.
- Red Oni, Blue Oni: The Red (bad cop) to Sumio's Blue (good cop).
- Straight Gay: Suggested by the Ship Tease between him and Sumio; in Flower, Sun and Rain, this is confirmed, at least according to Tokio.
- Armored Closet Gay: ...which puts a different perspective on Tetsu referring to Kamui as a "fag".
Chizuru HachisukaThe mayor's daughter. A traditional detective who understands forensic profiling and data collection.
- All Periods Are PMS: This is what she blames her irritability on at the end of Spectrum, but given her turnaround in personality afterwards, this may be a bluff.
- Lack of Empathy: She tends to come off as blunt and insensitive.
- Only Sane Woman: Her methods are the most realistic, yet the other detectives get praised for their intuition, much to her exasperation.
- The Smurfette Principle: Much to her annoyance.
- Tomato in the Mirror: She's the next iteration of Ayame.
Kiyoshi MorikawaChizuru's partner. An old friend of Kusabi's. Skilled, yet often comes across as lazy or temperamental.
- Bunny-Ears Lawyer: Very respected in the department, but it can seem like he's not doing much of anything useful.
- Driven to Suicide: Right after he talks to Akira for the last time in the underground complex, he throws himself in the path of the train that leads to the Triangle Towers.
Morichika NakategawaA loner who works from the office.
- The Aloner: He might carry a gun, but he's rarely assigned to work outside the HCU building.
- Big Bad Friend: He's not disloyal to the HCU and his co-workers, but he also happens to be high-ranking for the FSO.
- Lolicon: He implies as much on a few occasions, which just makes him all the more creepy.
- Rank Up: Is promoted to the chief of the HCU in the climactic chapter.
Akira/???You. A former member of the Republic task force, you are recruited into the HCU following the former's near-destruction.
- Embarrassing Nickname: Subverted; although Kusabi's nicknames for Akira (first Chinchilla and later Big Dick (yes, seriously)) seem... questionable, Sumio actually thinks they're cool.
- Face of a Thug: Whenever his face is actually shown, we see that he is pale, his eyes are hidden and has a scar.
- Hello, [Insert Name Here]: When starting a new file, the game will ask "Who Are You?", at which point you type in what becomes your codename.
- Heroic Mime: Deconstructed. He can't talk due to suffering from psychosis following his failed mission, and rather than heroic, people find it intimidating and creepy. In Whiteout prologue, this is actually a problem as he's unable to answer Shiroyabu, who shoots him because of it.
- Only Known by Their Nickname: It seems that he doesn't actually have a real name.
- Sudden Sequel Death Syndrome: In a sense; the 2016 remaster's new "Whiteout" prologue chapter ends with him seemingly being shot to death by Shiroyabu.
- Tomato in the Mirror: You are the next iteration of Kamui.
Sakura NatsumeAn ex-Republic operator who got transferred to the HCU, and the daughter of Republic's former chief Daigo Natsume.
- The Chief's Daughter: To Republic.
- Faux Action Girl: She barely gets deployed during her time with Republic.
- Logical Latecomer: She is unfamiliar with how the HCU operates, which has her taken aback. This is completely subverted by the climax of Lifecut, though, as she learns about the truth behind the Silver Case.
- New Meat: A recent transfer from Republic.
- Sixth Ranger: The most important and prominent of the new additions to the Unit.
Riley KawabataThe medical examiner in charge of conducting autopsies.
Shinji KotobukiThe boss of the HCU.
Daigo NatsumeThe head of Republic. As of shortly into the game, he's confined to the IMM Hospital due to serious injuries sustained in the case.
- Authority Equals Asskicking: Averted. Despite being in the field, Kamui (Ayame) was able to severely injure him so that he ends up in an apparently permanent coma.
- Da Chief: Head of Republic.
Kenichi SakamotoThe second in command of Republic. Responsible for leading a Republic element to arrest Kamui in "Operation Secure Kamui".
- Number Two: Second in command of Republic.
Haruhiko InomataA Republic operator. He's very skeptical that arresting Kamui is easy to do.
- Tempting Fate: During the debriefing, Inomata keeps insisting that arresting Kamui may be very hard to do since he kills anyone standing in his way. He's one of the first to die in the line of duty.
Tokio MorishimaThe protagonist of the Placebo side of the story, Tokio is an introspective freelance reporter who lives in a small apartment with his pet turtle. Although Tokio is only a private citizen, his investigations into the events of the Transmitter side embroil him further and further into the main story.
- Adorkable: Although he sees himself as cool, he often ends up embarrassing himself.
- Heroic BSoD: After the attempt on his life in "AI", he lends away his turtle Red and becomes completely detached from everything to the point that he doesn't answer his e-mails for a whole month.
- Long-Lost Relative: Subverted; he's this to the Hachisuka family, but by the time he learns this Chizuru is already dead and they never actually met.
- Luke, I Am Your Father: He's actually the son of Mayor Hachisuka, but he doesn't know it as he was adopted by another family.
- Smoking Is Cool: He seems to think so, at least. Placebo cigarettes in particular seem to be his favored brand.
- Un-person: He intends to invoke this by the end of "Hikari".
RedTokio's pet turtle and his closest companion.
- Cool Pet: Tokio thinks so, but he has a hard time convincing people of it.
- In *3: TSUKI (Part 1), while a construction crew is making an inordinate amount of noise, the upset Tokio tries to invoke this by asking Red to "grow really huge" and attack the crew outside. Red, however, is terrified by the noise, refusing to eat.
- Morality Pet: Quite literally. He's one of the few individuals that don't mind Tokio in the present.
Kamui UeharaA legendary serial killer/assassin from twenty years ago, he was notable for killing individuals who had done some evil in the past, always in the middle of winter. His crimes came to an end when he was caught and arrested in the incident known as "The Silver Case". Following his arrest, he has been in and out of the hospital for the past several years. However, at the onset of the game, multiple signs are pointing to his reawakening.
- Big Bad: Set up as this. Subverted, though; in his current state he's unable to do anything, and by the time he does become active (much later in the game) you've become well aware that something bigger is going on.
- Cassandra Truth: Kamui being unable to kill, let alone do anything, is first disclosed by IMM Hospital staff Tachibana. Kusabi vocalizes his dismissal of this claim, given that Kamui's counselor has turned up dead, ostensibly by Kamui's hand. Then when he's brought into the HCU headquarters, he find that Kamui really can't do anything.
- Dark Messiah: This is how people see him, regardless of his unclear intentions.
- Dead All Along: The original Format Kamui was killed years ago.
- The Dreaded: Responsible for killing several people, including various government and corporate officials. He's known as the Angel of Absolute Zero for a reason.
- Empty Shell: When Kodai and Akira discover Kamui, they find a silent man who lacks any potential to kill anyone.
- Legacy Character: It turns out that there have actually been several Kamuis, created through transmitting the original's personality to people who are primed to receive it. All this time, the public is told that there is only one.
- Vigilante Man: Some of the profiles seen in the game describe him as only killing other criminals who had avoided proper procedure under the legal system.
- Villain with Good Publicity: Some parts of the public paint him as an anti-hero who goes after the corrupt and the abusive.
- Walking Spoiler: Suffice to say that Kamui is not at all what the game says he is.
Ayame ShimohiraKamui's digital artist partner during a time when he was out of the hospital. The HC Unit takes an interest in her due to all signs pointing to her being the potential next victim of Kamui's reawakening.
- Cop Killer: Takes out the Republic task force in Operation Secure Kamui.
- Dark Messiah: Although not as well-known as Kamui, those that are aware of her seem to revere her even more.
- Distaff Counterpart: "Ayame" is actually just the designation for females with the Kamui personality.
- Jack the Ripoff: Imitates Kamui in Decoyman, to the point that even the narration presents Kamui as the culprit.
- Killed Offscreen: It's implied that she dies between Parade and Kamuidrome.
- Legacy Character: See above.
- Meaningful Name: The verb "ayameru" means "to kill".
- More Deadly Than the Male: Deliberately invoked by the governmental experiment she was a part of.
- Walking Spoiler: Much like Kamui, except in her case even the fact that she's a killer is a spoiler.
The Bat (Kaiji Enzawa)A mysterious hacker who sends the protagonists threatening e-mails.
- Animal Motifs: That's "the bat" as in the animal, not as in the sports tool/weapon.
- The Dog Was the Mastermind: See below.
- Early-Bird Cameo: Enzawa appears early in the game as the Ayame fanatic that Tokio meets with in YUME.
- He Knows Too Much: He warns the protagonists not to get involved any more than they already are.
- Small Role, Big Impact: He seems to be a relatively minor threat in the grand scheme of things. However, in the Triangle Towers you eventually find out from the notes you find that he's the chief supervisor for the Shelter Kids experiments.
- Stalker Without A Crush: To both protagonists.
Uminosuke Hachisuka/Kaoru HachisukaUminosuke Hachisuka was the mayor of the 24th Ward at the time of the original Silver Case. Since then, he has been succeeded by his son Kaoru.
- Greater-Scope Villain: Uminosuke caused a lot of the plot by killing Kamui and stealing his silver eye. He's still around, but not directly confronted on-camera.
- He Who Must Not Be Seen: Uminosuke isn't clearly shown onscreen at all, except at the very end of Hikari.
- Karma Houdini: While he appears to play this straight, the cliffhanger at the end strongly implies that he wound up being killed by the latest Kamui. To add insult to injury, Tokio has seemingly stolen his left eye.
- Kill and Replace: Uminosuke to Kaoru.
- Luke, I Am Your Father: To Tokio. Subverted in that he only reveals this indirectly, but Tokio still realizes it.
- Walking Spoiler: It's hard to talk about them without revealing that for the most part, they're one and the same.