Akuma no Mikata

Kou Doujima is an ordinary high school student. But his childhood was far from something we would call ordinary, and it left a mark on him for the rest of his life. He claims to have witnessed his little sister kidnapped by a UFO. Of course, no one believes him. He is bullied most of the time and, having nobody to rely on, has no choice but to endure the situation by himself. He manages to, but as a result he became incapable of trusting anyone but himself. One day, a little girl knocks on his door and she says, “I’m the devil. I have granted your wish and I’m here for your soul.”

(Source: tanoshimi.xyz)