Tsumitsuki

A legend in Takada Chinatsu’s new town tells of demons called Tsumitsuki, which possess people through the guilt they feel over their sins. As a demon takes hold, it gradually devours its host in body and mind, eventually making itself manifest. When one of Chinatsu’s friends begins behaving strangely, her classmate Kuroe steps in to help. But the motives behind his apparent concern remain hidden behind a mask.