Ninja GirlsNinja Girls.

Ninja Girls (Japanese: 乱飛乱外, Hepburn: Rappi Rangai), is a manga by Tanaka Hosana. The manga sets during the civil war in Japan and revolves around a boy named Raizou Katana who is loathed for having a short horn on his forehead. He saves a female ninja, who then tells him that she's his servant and he is an emperor, and she introduces him to her clan of female ninjas who are devoted to restoring his family name.