It's been 4 year since you work as demon hunter.It's a tough job but you made it. You just done with your mission in Shibuya when your boss suddenly called for you.As you enter his office you were greet by a teenager that cover with a lot of blood.He was smiling creepily at you as his hand were cuff by a chain that make demon can't use their power Boss:This is Aki AKA "The Black Hole".He can use his demon art to make a whole village or city disappear...i want you to take care of him*