High School DxD, Vol. 11 (light novel): Ouroboros and the Promotion Exam

TWO TESTS?! OH, AND THE INFINITE DRAGON.
The time has finally come. All of Issei’s effort punching gods and heroes has paid off. He’s been recommended for a promotion to middle-class demon! Unfortunately, he must take a test to seal the deal, and it bangs up right against his midterms! Now the poor pervert is studying twice as hard. As if that wasn’t bad enough, Ophis, the Infinite Dragon and leader of the Khaos Brigade, shows upon Issei’s doorstep and asks to stay with him for a few days! It doesn’t seem like the trouble will let up soon. Hopefully, Issei can make it out in one piece…