Mihashi, the main character of the series, is a nervous boy with no self confidence. He is shown to have always had this personality, (which seems to come in part from his father, who displays some of the same mannerisms) however, it became much more pronounced in middle school, where he was bullied by his teammates on the baseball team after gaining a place on the team apparently through favouritism, as his grandfather owned the school. The other members of the team were resentful of this and felt that their reserve pitcher, Kanou, was far more talented than Mihashi. However, Mihashi refused to give up the mound and pitched in every one of their games, even when his teammates stopped trying and the catcher wouldn't give him signs to throw. Eventually, Mihashi decided to change schools for high school and succeeded in gaining a place in Nishiura. Although he felt guilty for ruining his junior high teams enjoyment of the game, and thus promised himself he wouldn't play baseball in high school, Mihashi let slip that he was a pitcher, and is thus dragged into the baseball club, who had no other pitcher.
Although Mihashi is convinced that he has no talent, he has been practicing hard at pitching since elementary school, and his new teammates, in particular the talented catcher, Abe, are astounded at his highly accurate aim. When pitching, he divides his target into nine sections, which is said to be above the level of a professional pitcher, who would divide it into four. Mihashi also has four breaking balls, including unusual fastball which often confuses opposing batters. His pitches are said to be quite slow, although with training from Momoe his speed increases later on in the series.
Mihashi's relationship with Abe as a battery is often strained, with Abe quick to lose his temper and Mihashi fearful of angering him, however, Mihashi greatly respects Abe and is eternally grateful to him for wanting to be his catcher, noting that if it weren't for Abe's skill at reading the opposing team and calling for the right pitches, Mihashi could never make anyone strike out. Abe, in turn, appreciates how hard Mihashi works on his control and his dedication to pitching for the entire game. With his help, and the encouragement of his new teammates, Mihashi's confidence in his pitching as grown slightly, though he still firmly believes it would be nothing without Abe, to the point that Abe promises not to get sick or injured for their three years of high school, in order to be able to catch all of Mihashi's pitches.
Mihashi gets on well with the rest of his team mates, particularly Tajima, who always seems to understand him even when Mihashi can only stutter a few words. He was childhood friends with Hamada, who he calls 'Hama-chan,' and they lived in the same apartment building until Mihashi moved away. He is also close to his cousin Ruri, having lived with her family during middle school, though he dislikes it when she calls him 'Renren,' and is also friends with Ruri's neighbour, Kanou, who was his rival for the position of pitcher in middle school. Although he became more formal with Kanou in school, likely out of guilt for not giving up the mound to him, Kanou has always thought that Mihashi was a better pitcher than him. They are now on good terms again, and Mihashi calls Kanou by his childhood nickname, 'Shuu-chan.'
Despite his low self-confidence, Mihashi is very stubborn, refusing to give up the mound even when so exhausted that he starts losing control of his pitches, and becoming upset at the idea of the team needing a reserve pitcher. He is quite guillable, loves to eat, and has a fear of dogs. Mihashi's grades are very poor, and he says he had to work hard in order to get into Nishiura. He loves pitching so much that his mother mentions he's always holding a ball, even in his sleep.
