Kazuma Ikezawa (池沢 佳主馬Ikezawa Kazuma?) - The 13-year-old cousin of Natsuki Shinohara. His avatar is King Kazma, a renowned martial artist in the World of Oz. Kazuma is also a hikikomori who seldom leaves his room and uses his talents to win every game in Oz. But it's hinted that he does have friends, as more a spin-off manga made after Summer Wars telling about how he was able to become King Kazma. When he is not in his room, he trains in Shorinji Kempo with his grandfather, Mansuke Jinnouchi.
His appearance involves tanned skin, short messy black hair with bangs that cover his right eye. His eyes are a dark brown, nearly black, color. He is very short for his age. He's seen mostly with headphones around his neck or on his head and in front of a computer playing Oz.