Shin Megami Tensei [KAHN]

The terrifying manga based on the hit video game! Nobu is a troubled teenager with a dark past. His old high school was sucked into the Underworld, where he and his fellow students battled hordes of demons led by the Demon Lord, Hazama. However, Nobu and a demon-possessed girl named Yumi managed to claw their way back to the Surface World, hoping to start new lives at new schools. But it isn't long before Nobu uncovers a government conspiracy to raise Hell on Earth, and he and Yumi are once again forced to face their worst nightmares...
(Source: Tokyopop)