Saitō Yu'ichi, a young man without prospects, decides to kill himself at the turn of the year. However, a fateful encounter with a stranger, Mitsumune Sakutarō, who is his complete opposite, changes Yu'ichi's future in a way he could never have imagined.

Ikuo Ryuuzaki and Danno Tatsuya are 2 orphaned boys who were looked after by a person they called 'sensei'. Following their sensei's brutal murder, the two vow to hunt down the killers and the police officers who neglected to properly investigate the case.

15 years later, Ryuuzaki is a police detective and Tatsuya has become the leader of a group of mobsters. Helping each other out behind the scenes, they strive to rise to the tops of their respective fields so that they may exact their vengeance.