Kami nomi zo Shiru Sekai

Katsuragi Keima is known on the net as the god of getting the girls while in real life he’s known as otamegane and he hates all real girls. However he is approached by Elsie, a devil from hell, to help her in catching runaway spirits that hide in people. Apparently the spirits only hide in the hearts of girls and the only way to get the souls out is by making the girl fall in love so the spirit gets forced out. And he’s not allowed to fail or he will lose his head. (Source: MU)