Humanoid Monster Bem(1968)

Youkai Ningen Bem

Three monsters, Bem, who looks like a gangster, Bero, who looks like a boy, and Bera, a witch, act as agents of justice, hoping that they will be allowed to become human. Several episodes involve them protecting a young boy. The style of animation is fairly distinctive, and the storylines not without interest.

(Source: AniDB)