Ichi may seem like a spineless weakling—but when the tears start flowing, a terrifying transformation takes place. Driven to his mental breaking point, Ichi becomes an unstoppable force of carnage, unleashing a torrent of violence on his next target. When his destructive path collides with Kakihara, a sadomasochistic yakuza boss with a penchant for pain, it ignites a bloody spiral of chaos, depravity, and unimaginable brutality. (Source: Seven Seas Entertainment)

In 2001, Koroshiya 1 was adapted into a live-action film which was directed by Takashi Miike. The series has been published in English as Ichi the Killer by Seven Seas Entertainment as 2-in-1 omnibus volumes since July 29, 2025. It has been published in Spanish by ECC Comics since February 20, 2015.