High School DxD, Vol. 4 (light novel)

Guess what? I, Issei Hyoudou, am now a mentor to a new junior in theOccult
Research Club! Yeah! Demon Lord Sirzechs had the Prez add a Bishop toher 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 eversaid high school was going to
be easy!