High School DXD Light Novel Volume 4 (Mature)

Guess what? I, Issei Hyoudou, am now a mentor to a new junior in the Occult Research Club! Yeah! Demon Lord Sirzechs had the Prez add a Bishop to her Familia. Wait...He's a what? He was sealed where? Huh? The Demons, Angels, and Fallen Angels are having a meeting...here?! Well, no one ever said high school was going to be easy!