Hunt of a New Wolf (1999)

Asakura Tetsuya is a man who leads a double life. By day, he is a mild-mannered and affable salaryman in the Mogi Corporation. Come night, he takes on the persona of a hardened and violent individual bent on exposing the shady dealings of his company. Tetsuya's brother was a former president of one of the Mogi subsidiaries, but committed suicide under mysterious circumstances after some company trouble. Tetsuya is convinced that a company conspiracy staged the suicide, and he is obsessed with finding out the truth in order to avenge his brother.