Using Ichi as a tool, Jii-san plots to kill Anjougumi's Kumichou and steal his money. With Anjou's death, Anjou's top yakuza, Kakihara, sets out to find his Kumichou's murderer. While Kakihara searches for Ichi, Ichi effortlessly kills off remaining members of the Anjougumi. This continuous cycle of killing and searching leads the two closer together revealing Ichi's psychological manipulation and Kakihara's obsession of pain and torture. When the two finally meet, the two confront their deepest and suppressed desires resulting in Ichi's psychological recovery and Kakihara's demise.
Characters
Ichi is the main character in the series. He is psychologically and emotionally disturbed to the point where he acts as a child living in an adult's body. When faced with a confrontation, Ichi bursts into tears and breaks down emotionally. Even with his cowardly personality, Ichi has trained extensively in the martial arts. With this training, a concealed blade in his left boot, and a psychological kill switch, Ichi turns into a ruthless killer hunting down yakuza with a streak for sadism.
Kakihara Masao is a yakuza boss and Ichi's prime enemy. He is tired of everything in life and lives to inflict pain on others and even himself. His most notable characteristics are the deep gashes on his cheeks. These gashes allow him to open his mouth to ridiculous levels in a snake like fashion and they are subsequently held together by piercings. He lives his life for sadomasochism.
Jii-san is the mastermind behind the unrest in the Anjougumi family as well as the puppet master making Ichi kill. He claims to have gained his aged features through plastic surgery and to still be in his early thirties. Has an extremely muscular physique and abuses steroids.
Anjou Yoshio is the head of the Anjougumi yakuza family. His murder, which is first disguised as a disappearance, leads Kakihara to search for Ichi.
Noboru is a member of Jii-san's group whose weapon is a firearm.
Inoue is an excommunicated member of the Anjougumi and a current member of Jii-san's group. He is also a heroin addict that has undergone plastic surgery to remain hidden in Shinjuku.
Suzuki is a member of the Funaki yakuza family. He is accused of kidnapping Anjougumi's Kumichou. He is bedridden by the resulting torture and is convinced by Jii-san's group to employ them to eliminate Kakiharagumi.
Kaneko is Anjougumi's hitman and one of Kakihara's closest henchmen. He exhibits a fear similar to Ichi's and desires to prove himself. He is also Takeshi's father.
Norio is a young boy who goes to the same martial arts dojo as Ichi. He constantly gets beat up and goes to Ichi for help.
Seila is a prostitute that Ichi frequently visits. She has many bruises that are inflicted by her pimp, leading Ichi to have flashbacks of his past.
Karen is a hostess and one of Kakihara's friends. She assists Kakihara in locating members of Jii-san's group.
Tachibana is a girl from Ichi's first year in high school. When trying to save Ichi from bullies, she was ostracized and raped.
Long is a Chinese member of Jii-san's group that works as a gigolo.
The twins are members of Kakihara's former kumichou Atougumi. They are as competitive as they are sadistic, often resulting in shows of one-upmanship fatal to others. Jirou has inhuman strength, while Saburou is good with a short knife.
Takeshi is Kaneko's son and often witnesses Ichi crying after his murders. He is also Ichi's successor as the next "killing machine" manipulated by jiji.
Media
Manga
The manga has been compiled into ten volumes by Shogakukan. There is also a prequel titled Ichi.
Films
The manga has been adapted into a film of the same name directed by Takashi Miike and the prequel into a film called 1-Ichi by Masato Tanno.
Anime
The manga has also been adapted into an OAV called Koroshiya 1: The Animation Episode 0.
Reception
Reviewing the OAV, Theron Martin from Anime News Network felt that the story is "perfectly believable" and "convince the viewer that Ichi's lethal tendencies didn't come from nowhere" because it follows the "common elements you hear about in the backgrounds of true killers". He dismissed the "substandard animation" as problematic but praised the music of "heavy driving techno themes" that provide an "edgy mood and tone for the series".
