A student of Gehenna Academy, Ako is the executive officer of the Disciplinary Committee, and a sort-of secretary to its president Hina. At first glance she may appear kind and good-natured, but Ako has zero tolerance for students who break the rules. She is constantly at Hina's side, assisting in her duties as president of the Disciplinary Committee. This has prompted other students to call her "Hina's Pet" amongst other things, but Ako doesn't particulary care.