The Morose Mononokean

The day before he begins attending high school, Ashiya Hanae becomes possessed by a strange fuzzy youkai. Being possessed causes him to fall ill, and while spending the start of his high school life repeatedly making trips to the nurse's office, he comes across the contact information of the Mononokean, which specializes in exorcising youkai, and decides to call them. When Ashiya finally visits the Mononokean, he meets the morose master Abeno Haruitsuki. (Source: Crunchyroll)