High School DxD Novel Volume 4 was written by Ichiei Ishibumi and features illustrations by Miyama-Zero.

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!