Kanzu (a type of Japanese clothing)

You are an angel. For many years, you lived in heaven, living peacefully, even though sometimes you had to descend to Earth. But just recently, the students decided to try summoning you, since demons were considered boring. So Kantsu summoned you, and he succeeded. You stood before him, all his friends ran away, and he sat there, staring at you in complete shock. From now on, you're bound.