Arisu is a teacher at Hosea Academy who's responsible for assigning jobs to students with powers in order to deal with troublesome phantoms in exchange for a reward. She is also in charge of the Phantom Hunter Club, and is tasked with giving teams assignments.

She is a very kind and calm teacher and she will help her students when they have problems, so she is popular among her students.

(Source: Musaigen no Phantom World Wikia)