- Adaptation Displacement: The film of the manga.
- Complete Monster: Ichi the Killer is a twisted manga, as these characters demonstrate:
- Masao Kakihara, a twisted Combat Sadomasochist whose boss is murdered by the titular Ichi, begins a hunt for the mysterious assassin in his obsession to discover the ultimate pain. Kakihara participates in a number of murders of Yakuza and civilians alike and has no compunction allowing rape or torture to occur under his watch. Cold-Blooded Torture is his specialty, in fact, and he tortures one man by hanging him from multiple needles and hurling hot tempura oil over his bleeding back. Obsessed with the point where pain and pleasure meet, Kakihara terrifies all who meet him.
- Kakiharas Co-Dragons, Jiro and Saburo, brag that they've raped hundreds of women. Driven to outdo one another, they introduce themselves by asking a pair of lovers who the women preferred in bed. When the women give an answer, the offended twin viciously tortures and kills them. The two later abduct a prostitute after brutalizing her and rape her to get her pimp to talk. Despite Kakihara's orders not to kill them until he verifies their information, the two play a game to see who can hurt the two worse solely to prove who's better at causing pain. When one accidentally kills the pimp, the other kills the girl just to prove he can kill someone as well. After Ichi kills Jiro, Saburo is only angry because he wanted to kill his brother himself one day. He then proceeds to kill a man Kakihara tortured earlier and rapes and murders the girl with him, before killing her with a knife through her genitals.
- Crosses the Line Twice: For the most part the manga series just stay past the line, dark, gritty and brutal, but then you get to the point where a crying Ichi chases after a nude, bleeding and split-dicked masochistic mafioso and the scene gets described as "romantic", framed in a bubble shot and all at that point it just swings around to twistedly funny.
- Darkness-Induced Audience Apathy: Ichi treads perilously close to this trope. Everyone of plot significance is a depraved pervert, murderer, psychopath or manipulative bastard (and that's an INCLUSIVE "or," people!). There's really no character you can feel good about rooting for. Even Jiji, the puppet master whose scheme to destroy Kakihara's Yakuza clan could be seen as dolling out justice in a round about way is, by the end, unmasked as a nihilistic maniac whose only real motivation for taking on the Yakuza was the pure amusement of the challenge. Ichi's cocktail of black versus black morality, horrific violence and buckets of squick can definitely be hard to stomach at times. Arguably averted (opinions are apt to differ considerably here) due to the extremely tense, coiled plot, and Ichi the Killer's surprisingly incisive philosophical musings.
- I Am Not Shazam: Kakihara is usually the one shown in advertising of the comic and movie - sometimes they even put a "1" on his face. The titular Ichi, on the other hand, is a sobbing weakling wearing a stuntman suit.
- Narm: The faces of many of the characters are drawn in a somewhat comical and exaggerated way, diminishing the terrifying effect.
- Nightmare Fuel: At least one instance per chapter.
- Special Effects Failure: Any time Kakihara drops his jaw in the film. Really unfortunate, as it's otherwise effectively REALLY disturbing.
- Squick: Can't have Gorn without it.
- Tear Jerker:
- Ichi's memories of horrendous abuse in his high school, which the cunning Jijii uses to drive Ichi into a teary-eyed Roaring Rampage of Revenge against bullies.
- Ichi's relationship with the poor abused prostitute in the manga. It's painfully clear that he really sympathizes with her, but can't control his own violent insanity.
YMMV / Ichi the Killer