Three years ago, a disappearance case, known as the "Joker Case," was suddenly closed without being solved. Ichiro Kunishita, an investigator from the Public Security Bureau of the Tokyo Metropolitan Police Department who was called for a reunion of the investigation, is ordered to take on a completely different mission. He is assigned to spy on and monitor Shiro Hanabusa, the young head of a designated gang clan. He is said to be a man of many mysteries who has risen to the rank of Wakagashira (young leading subordinate in yakuza group) since he joined the gang three years ago. In the course of his mission to get close to Shiro, Ichirou learns a shocking fact, and decides to make a fake "lover's contract" with him. Their secret investigation into the case gradually leads them to an incident that will shake the nation and their destiny.

Ai's mother sends her to live with a cult commune, where she remains for seven years. After the cult is broken up by the police, Ai struggles to fit in with society.

Slacker Ichiko gets into a fight with her younger sister and begins to live on her own, working the late shift at a 100 yen shop. On her way home, she passes a gym and meets middle-aged boxer Kano who trains there in silence...