A child with a strange illness that makes him unable to see any name, face, or any other kind of personal identifier. The illness will also kill him when he turns 12 years old. The boy sees personal identifiers blocked out with a black ink. The boy has a dark and twisted personality, often thinking of ways to kill the girl. He believes that individuality is more important than anything, so most people mean nothing to him as he can't see each of their individualities. Even with the boy's personality, he does have some emotions; as he got attached to the girl with the same disease as him, worrying that he may not be able to kill her. When the boy learned that he had the disease, he was ecstatic about it. He'd be remembered as the first person to die from it, which would make him important, in his eyes. Once he learned about the girl suffering from the same disease and that she'd die before him, the boy plans to kill her before the disease does.

Spoiler

After he dies, the boy, along with the girl are named Shou Yamai (山井症). Their real names are unknown.