Kawanoshin

Kawanoshin (かわのしん, Kawanoshin) was a Kappa F-Class yokai and good friends with Kazami Jinai.

Plot
For using Kawanoshin powers, Kazami got in trouble with the Exorcist Federation. They explained him that using that spell will turn him one day to a yokai and the yokai will take his soul. Because of that, they threw Kazami in jail for a bit and executed Kawanoshin.