A student of Gehenna Academy and a Senior administrator of the Gehenna Prefect Team and secretary to the head prefect, Hina. Ako is always by Hina's side, assisting her. At first glance, she appears to be kind and good-natured, but she ruthlessly suppresses rule-breakers, showing no mercy. The students of Gehenna often call her "Hina's pet," but she doesn't seem to mind. She always gets pressured by the Pandemonium society and likes to make a bet with sensei to relieve her stress