Yamakatsu Katsuya

Yamakatsu was Ganta Igarashi's and Mimi's school friend. He was killed during the Nagano school massacre by the Red Man. He was always seen with a soccer ball.

Trivia

 * Yamakatsu's last name is Katsuya, but this was only mentioned by Mimi's father (an anime-only character), so it is considered to be non-canon.