Ryousuke Kominato is a third-year student at Seidou High School and the starting second baseman for the baseball team. He's probably best known as Haruichi's older brother, though he's carved out his own reputation as a solid defensive player in his own right. The two brothers play together on the same squad, which isn't uncommon in baseball anime, but their dynamic is worth noting—Ryousuke's the more serious, methodical type compared to his younger sibling's personality.
Content compiled by AnimeList.moe from publicly available sources.
