Kotake Ryo is a rogue detective in the Violent Crimes Division of the Seihoku Ikebukuro Police Department's Criminal Investigation Division. He is known to be the type of person who gets extremely involved in certain cases. Saeko, whom he once took into custody as a delinquent, has been murdered. With just one word from Ryo, she was serious about reforming and trying to become a nursery school teacher... I can't forgive this! Enraged, Ryo, with the help of Saeko's female friend and Saeko's boyfriend, Tokita, discovers that the Nanaoki-kai is forcing girls into prostitution on a cruiser floating on the sea. Ryo goes in alone...