Keisuke Yamanoi (梅原圭介 Yamanoi Keisuke) is the center fielder of Tosei High School's baseball team.
Yamanoi is among the students who witnessed their team lost in the first match when he was a freshman.
All of his teammates call him Yama-chan, including the juniors.
He has black hair and his face usually displays a calm expression.
Yamanoi is an incredibly relaxed person who always keeps his emotion under control. While the rest of the batters was weirded out by Mihashi’s pitching, he remains unfazed whenever it is his turn to bat.