Ton-chan's basically the friend-and-rival type to Shuutaro, and he's genuinely obsessed with baseball—like, it's his whole thing. Ryoko has a pretty obvious crush on him, though he's probably too focused on the sport to notice.
His character design is a deliberate nod to classic 70s sports manga aesthetics, particularly *Kyojin no Hoshi*. Those literal stars in his eyes? That's the joke—a visual gag poking fun at how melodramatic and wide-eyed those old protagonists used to get whenever they found their passion. Ton-chan's just the modern, more comedic take on that archetype.
Content compiled by AnimeList.moe from publicly available sources.