Murakami Yasuharu

He had been changing schools for a long time, but started to get bullied when he entered a junior high school, and has been bullied ever since. His parents are divorced, so he lives with his mother. Feeling cornered and wanting to die, while looking for a way to die comfortably, somehow, he ends up on a website about demon summoning. He is able to summon it, but he gets a monster instead whom he later merges with in order to avoid dying due to an accident. And because of that, he now has the mean to take revenge on the person who bullies him.