Kumagai is the teddy bear partner of Momiji's who communicates by writing in a book.
Kumagai is created by Yoshiaki Sukeno as the supporting character in the Binbogami Ga! manga series. The teddy bear has no information regarding any inspiration used by Yoshiaki Sukeno for its creation. It makes her first manga debut in volume 1: chapter 2 and first anime debut in episode 3.