War in the Shadows (2014)

In Tokyo, where a massive underground organization moves in the shadows, Yoshioka (Takashi Kitadai) is suddenly released from prison after serving time for murder. His mission: infiltrate the organization and leak information to the police. The one who orchestrated this is Detective Harada (Kazuyoshi Ozawa), who hires the ex–hangure Yoshioka as a kind of "covert civil servant" due to his deep knowledge of the underworld. As Yoshioka digs deeper into the organization, he rises through its ranks — but what awaits him is a shocking and unforeseen conclusion.