Despite his lazy and at times comical nature (comical due to his laziness and arguments with Mahiru), he is shown to have a dark side. This is shown whenever anyone try to bring up his past that involves him killing the creator of Servamps. The mere mention of his past was enough to make Kuro who usually is nonchalant to become aggressive. He views himself as a monster, a fact that he dislikes, which caused him to refuse finding out more about his own race as it'll prove further how much of a monster he and his siblings are. He also refuse to turn any humans into vampires to make them his subclass, saying that they probably didn't want to become vampires, and that vampires shouldn't even exist.