Oto X Maho

Junior high schooler Shirahime Kanata is forced by his mother, Konata, into a contract that lets him transform into a magical girl. If he cancels it, however, he will change gender and become a girl. Now known as Kana-tan, Kanata fights monsters called Noise alongside his tiny supervisor, Moel. He must wear spats while battling them, all while trying to hide that he is a boy.