Matsuyoi no Oni

From a young age, he is bewitched by the supernatural. One day, he picked up a strange dog collapsed near his home. It turns out that this dog was actually a demon whose name was sealed and lost it's powers. He suddenly said "I finally found you". By some kind of fate, he is needed to gain powers. The only way he can be on human form is to form a contract. He craved for him from the depths of his body but the truth is he was just being played?!