One day, Tatsumi, a lonely underworld worker, comes across the murder scene of his ex-girlfriend Kyoko. Tatsumi escapes with Kyoko's younger sister, Aoi, who was with her. On the other hand, Aoi, who has lost her beloved family and vows revenge, pursues the murderer of Kyoko.

Tatsumi, who is at loggerheads with the impudent Aoi, decides to accompany her on her journey for revenge, and as he cooperates with her, a certain feeling begins to develop.