Yakuza Demon (movie, 2003)

Seiji and Yoshifumi are the only members of the Muto branch of the Date Family. The two respect and love their leader, Mr. Muto, like a father and the three share a firm bond. But their fate is sealed when the Family is involved in a conflict. Muto is unable to pay his share of funds for the oncoming battle but tells executives of the Family that he would fight at the front line instead. In the wish to protect Muto, Seiji has him arrested by the police. Ignoring the Family executives' mocks of "Muto escaped to prison", Seiji prepares for the battle and attacks like a demon on behalf of his boss...