Yamakatsu Katsuya

Yamakatsu was Ganta 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.

Yamakatsu's last name is Katsuya, but this was only mentioned by Mimi's father (an anime-only character), so it's not canon.

Yamakatsu is voiced by Shohei Kajikawa in the Japanese version and by Micah Solusod in the English version.