As sadomasochistic yakuza enforcer Kakihara searches for his missing boss he comes across Ichi, a repressed and psychotic killer who may be able to inflict levels of pain that Kakihara has only dreamed of.

One night in Tokyo, Leo, a young boxer, meets his first love, Monica, an imprisoned sex worker. Caught up in a drug-smuggling scheme, they find themselves pursued by a corrupt cop, a yakuza, his nemesis, and a female assassin.

Ninagawa is a powerful man in Japanese politics and with top economic connections.His granddaughter is then murdered. The suspect is Kunihide Kiyomaru. Kunihide Kiyomaru has a prior conviction for assaulting and killing a girl 8 years ago. The police could never apprehend the suspect in the prior killing.

In order to settle a business dispute, a mob leader murders one of his own teenage sons. The surviving son vows to avenge his brother's death, and organizes his own gang of teenage killers to destroy his father's organization.