|Birthday||May 12 (anime) / May 17 (manga)|
|Height|| 165 cm (debut)|
166.5 cm (since chapter 66)
|Weight|| 53 kg (debut)|
50 kg (episode 25 of season 1 until episode 6 of season 2)
|School||Nishiura High School|
|Year and Group||Year 1, Class 9|
|Family||Father, mother and cousin.|
|Anime||The Real Ace|
|Manga||The True Ace|
|English||Sean Micheal Teague|
Ren Mihashi (三橋 廉 / Mihashi Ren) is the main character in Big Windup!. He is the pitcher of Nishiura High school baseball team whose nervousness and extreme lack of self-confidence is at odds with his skill, a result of his passion and dedication to pitching.
During middle school, Mihashi was bullied by his teammates on the baseball team after gaining a place on the team apparently through favoritism. The other members of the team were resentful of this and felt that their reserve pitcher, Kanō, 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 team's enjoyment of the game, and thus promised himself he wouldn't play baseball in high school, Mihashi let it 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 high accuracy. When pitching, he divides the strike zone 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 an 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 is often seen anxious and has a very low self-confidence. He is shown to have always had this personality, however it became much more pronounced in middle school during the time when he was bullied by his teammates on the baseball team. He has struggles on saying his opinion which often leads to Abe's irritation.
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. He also feels upset at the idea of the team needing a reserve pitcher. He loves pitching so much that his mother mentions he's always holding a ball, even in his sleep.
Mihashi's grades are very poor, and he says he had to work hard in order to get into Nishiura. Despite his clumsiness, he is also shown to have a talent in cooking; he is confident enough to tell Abe what to do in the kitchen. He is quite gullible and loves to eat.
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. He notes 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 has 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.
He 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. Tajima often acts like a big brother to Mihashi, protecting him and getting angry if he thinks Mihashi is being bullied.
He and Hamada were childhood friends. 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'.
He is still friends with Kanou in spite of being rivals 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'.
- Mihashi has a fear of dogs.
- Mihashi, surprisingly enough, likes girls in nurse outfits.
- Main Artice: Ren Mihashi/Gallery