Crimson Prince, Volume 1 (Crimson Prince #1-3)

Demon prince Koujirou Sakura comes to Earth, enrolling in high school, on a mission to find the human who will threaten the future of the demon realm... and steal their souls! But with no clue as to this human's identity, Koujirou is at a loss. To make matters worse, the boys' dorm at his new school is full, and he's forced to live off campus with a girl! Oh, the humanity...!