The Seven Mysterious wonders of Kuoh Academy(駒王学園の七不思議; Ku-ō gakuen no nanafushigi); or simply The Seven Mysteries, is a recurring secondary chain of events in Highschool DxD: Яe-birth. First introduced during the events of Volume 5, for the next volumes up to the 7th, it'd take a secondary stage between the events of the "Miyama Runaways" Arc and the "Devil/Vampire peace conference" Arc.