Rapdevil is a Regular falsely nicknamed "Devil of the Right Arm" because of his ability to transform his right arm into a black and blue striped 'Power mode'. He had been hired to travel with a rich company owner's son. He claimed to have defeated Hatsu, who apparently is a well-known swordsman and Regular in the Tower. However, it is later revealed that he is in fact only a fake, using the reputation of Beniamino Cassano, the real Devil of the Right Arm.