Directors who work from their own original screenplays are a rare breed in Japanese cinema, and few have a voice as distinctive as Keisuke Yoshida. His films meld social realism with a mordant comic streak that can sometimes border on flippancy, making audiences giggle and squirm as he probes the contradictions of human behavior.

As a writer, Yoshida can give the impression that he’s setting out without a clear destination in mind, letting the material lead the way. “Mentor,” his second film this year, seems at first like a companion piece to the first, “Unchained.” But while it revisits a few of the same themes (the limits of rehabilitation, the feasibility of forgiveness), it ends up in an altogether unexpected place.