Fuka Sakurai: Lewd Fallen Angel(2002)

University student Yusaku has no idea what he wants to do and spends his days drifting around. One day, on his way home after drinking, he bumps into a girl. Yusaku chases after her. He finds out that the girl has been in an argument with a yakuza-like man and is about to be taken away by force. He tries to help her, but is punched by the man and falls to the ground. Yusaku has not been able to forget about her...