Tokyo is a dark technopolis, a city of faceless chrome and cold marble. It is ruled by Nogi, a yakuza boss specializing in drugs and murder. He gained absolute power by executing the former boss and marrying his daughter, Chiaki. Only the mysterious Ikko, Chiaki's half-sister threatens him. Inspired by a legendary hit-woman, Ikko calls herself the Black Angel and plans to wash away her father's murderer with a deluge of blood.

A son quits his job and is persuaded by his father to head off to a cottage in the remote mountains. Together, the two of them manage to get through their days while wearing old jerseys left by a deceased grandmother. The following summer, the two once again leave the stifling heat of Tokyo, as if escaping to the mountain cottage. However, the next summer is very different.