- David Versus Goliath: To Tousei in the first game.
- Foil: Nishiura's battery to Sakitama's battery.
- Underdogs Never Lose: Subverted. They lost to Bijoudai Sayama in Season 2.
Mihashi RenThe Protagonist. He was bullied at his former middle school due to his old teammates believing that he was made the ace through favoritism, because his family owns the school. He is actually a very talented pitcher, with a large variety of pitches and excellent control, but his pitches are slow and his talents aren't easily recognized without the cooperation of the team.The bullying he received left him an extremely shy, nervous, stuttering emotional wreck. (He gets better.)
- The Ace: He was the ace pitcher in Mihoshi and Nishiura line up.
- Broken Ace: In Mihoshi.
- Affectionate Nickname / Embarrassing Nickname: His cousin Ruri calls him "Ren-Ren", which he finds it embarrassing. His teammates laugh at it and Tajima teasingly calls him it when he hears it.
- All of the Other Reindeer
- Apologizes a Lot
- The Atoner: Mihashi is determined to make up for monopolizing the mound at Mihoshi by becoming a "real" ace this time.
- Big Eater
- Big Fancy House: which he lives in with his family.
- Book Dumb
- Bunny-Ears Lawyer
- Cannot Spit It Out: He really struggles saying how he really feels about a situation and struggles even more when he tries to tell Abe and everyone how much he appreciates them.
- Character Development
- Chaste Hero: Averted. Either naturally or under Tajima's influence, the manga reveals him to be more of a Covert Pervert.
- Cowardly Lion
- Determined Defeatist
- Dojikko: Improves with time
- Extreme Doormat
- Face Your Fears: During Tousei's matchMihashi: There's no place to hide on the mound.
- Foil: To Haruna; the battery he forms with Abe is foiled by Sakitama's battery.
- Four-Temperament Ensemble: supine.
- Fragile Flower
- Friendless Background
- Friendly Rivalry: With Kanou, Mihoshi's pitcher and his childhood friend.
- Guilt Complex: He believes it was completely his fault that Mihoshi lost every game in middle school.
- Heavy Sleeper: When he's really tired.
- Heroic Self-Deprecation
- Heterosexual Life-Partners: With Abe, though with lots of Homoerotic Subtext.
- It's All My Fault: Has to be repeatedly told by Abe that it's not.
- Japanese Honorifics: He refers to everyone on the team with the honorific "-kun".
- Lonely Rich Kid: At the start of the series. To the point that he has to trick his teammates into coming to his birthday party.
- Lovable Coward
- Naughty Nurse Outfit: Is later revealed to have a nurse fetish.
- Nervous Wreck
- The Nicknamer: Calls Kanou "Shuu-chan" and Hamada "Hama-chan".
- Not Love Interest: His thoughts revolve around a) pitching b) if A-a-a-be-kun is currently pleased with him or hates him.
- Odd Friendship: With Tajima.
- Sensitive Guy and Manly Man: The easily frightened Extreme Doormat to the no-nonsense, bossy Abe.
- Shrinking Violet
- Sleepy Head
- The Tell: How Hatake was able to hit his fastball.
- Unusual Eyebrows: They're squiggles!
- Weak, but Skilled
- Why Did It Have to Be Snakes?: Is scared of dogs.
- Workaholic: Has to be told not to practice past his pitch limit.
- Anger Born of Worry: Part of the reason why he snaps at Mihashi so often.
- Berserk Button: Mihashi's sniveling pisses him off.
- Big Eater: So much that he puts on 4kg in 3 days when healing up from an injury.
- Chaste Hero: He's one of the only boys who aren't fantasizing about girls and, as one omake reveals, have never fallen in love. And he's the only one around completely uninterested upon the discovery that Chiyo cleans up nicely. Poor girl.
- The Chessmaster
- Control Freak: To the point where even if it's almost always directed at Mihashi, even the other teammates find Abe annoying.
- Deuteragonist: The series is as much about him as it is about Mihashi.
- Face of a Thug: More like a facial expression of a thug. Abe appears constantly irritated even when he isn't, which makes the more shy team members get timid around him.
- Fan Nickname: Known among Japanese fans as "Kimobe" i.e. 'kimoi'(creepy)+ Abe. Comes with custom smiley: 仝ω仝
- Gay Moment: After he tells Mihashi he likes him not just as a pitcher but as a person, Mihashi "confesses" him back and Abe realizes how it all sounded.
- Hair-Trigger Temper: Has a very short fuse, especially around Mihashi; and since Mihashi becomes even less communicative when shouted at...
- Heel Realization: Realizes in episode 25 that his relationship with Mihashi is borderline abusive.
- Heterosexual Life-Partners: With Mihashi, willingly or not. Though many times the "heterosexual" part seems debatable.
- I Can Still Fight: After he sprains his knee in the Bijou match.
- I'm Okay: See above.
- Ineffectual Loner: Not in the games — he's cooperative and definitely not ineffectual — but has shades of this in his social life.
- Lethal Chef: Since his mother is a housewife, Takaya cannot cook. Which leads to an atypical situation, where Mihashi has to tell him what to do.
- Oblivious to Love Chiyo has a crush on him. Though to be fair, she resolved not to show it and does a good job, so it's not his fault for not noticing.
- NO INDOOR VOICE: Though he's working on it.
- Not Love Interest: Half of the series focuses at the ups and downs of his relationship with Mihashi.
- Parental Favoritism: His mother prefers her younger son Shun and will always go to Shun's games if both boys have a game on the same day.
- It's Personal: Between him and Haruna.
- Perpetual Frowner: His facial expressions range from indifferent to irritated (even when he doesn't actually feel it). When he demonstrated a wide grin to show his teammates what would be even better than a poker face, they were creeped out.
- Sensitive Guy and Manly Man: The no-nonsense, bossy one, contrasting with easily frightened Extreme Doormat Mihashi.
- Spiky Hair
- The Strategist
- Tareme: Although it doesn't give him a kind look, but rather an unimpressed one.
- Tempting Fate: Makes the reckless promise not to get hurt or sick for 3 years.
- Younger Than They Look: is one of the youngest guys on the team.
Position: First Baseman, Reserve Pitcher, Right Fielder (vs Sakitama)
Voiced by: Yuudai Satou (JP), Chris Cason (EN)
- Nonstandard Character Design: Has a nose looking like a potato.
- Shrinking Violet: He is the one to clue Abe in on the fact that his volume could be intimidating to Mihashi.
- The South Paw: The only left-handed person in Nishiura line-up.
Sakaeguchi Yuutonice guy. He's one of the other more experienced players on the team. He and Abe attended the same middle school, but they didn't meet until the day of the entrance exams.He is very good at bunting, and is described in canon as being closest to Suyama.
- Celeb Crush: Has a thing for Halle Berry.
- Missing Mom: She's "in heaven".
- Nice Guy: He's polite to everyone and manages to get along with Mihashi.
- Translator Buddy: Between Abe and Mihashi.
Position: Third Baseman, Reserve Catcher, First Baseman (vs Sakitama) , Catcher (vs Bijoudai-Sayama After Abe's injury)
Voiced by: Hiro Shimono (JP), Todd Haberkorn (EN)
- A Date with Rosie Palms: More than once a day is his normal regimen.
- The Ace: Not in the same way as Mihashi, though.
- Badass Boast: Claims to have never seen a pitch he couldn't hit in that game.
- Book Dumb
- Big Brother Instinct: Which elevated him to the one of the only people Mihashi doesn't fear.
- Big Eater
- Bunny-Ears Lawyer: Tajima is the most accurate hitter on the team and a baseball prodigy.
- Challenge Seeker: While the others will be pissing themselves when Hanai would have drawn another champion in the lottery, Tajima will be happy because of the challenge.
- Cloudcuckoolander: He doesn't seem to have a brain-to-mouth filter and occasionally strips in public; Hanai has to yell at him to make sure he doesn't get naked during practice where he can be seen from the street and Momokan has to stop him from getting naked in the stands at a game. And he pulls off Mihashi's swimming trunks to show off his 'grown-up dick'.
- Did I Just Say That Out Loud?: If it came from anyone else.
- The Ditz/Genius Ditz: He is very observant, has incredible memory and reflexes and thinks quickly — all of this talents he only utilizes in baseball.
- Establishing Character Moment: His TMI line at the beginning of episode 2.
- Even the Guys Want Him: Whenever Tajima does something amazing, a Nishiura team member will inevitably turn red and think, “He’s so cool!”. Also, everyone wants him in their team. And almost everyone wants to be him from time to time.
- Goofy Print Underwear: Orange boxers with blue dots in season 2.
- Heterosexual Life-Partners: With Hanai.
- Hormone-Addled Teenager: He masturbates several times a day.
- Hot for Teacher: Has said he would date Momokan if they were the same age.
- The Idealist: Though nobody's sure if it's from stupidity or optimism.
- I Thought Everyone Could Do That
- Jack-of-All-Trades: Without the Master of None factor — he's so exceptionally talented in every aspect of playing baseball that every player for whose position Tajima practices tends to feel threatened.
- Keet: Tajima is hyperactive.
- Let's Get Dangerous: Despite being hyperactive off the field, Tajima is extraordinarily focused during games.
- Massive Numbered Siblings: He's the last of 5 kids.
- Mundane Utility: Only uses his remarkable memory to remember baseball scores.
- The Napoleon: He's the shortest member of the team, standing at 164cm or just under 5'4.
- Odd Friendship: With Mihashi.
- One Head Shorter: Is more than a full head shorter than Hanai.
- Pintsized Powerhouse: He has the highest on-base percentage of the team which helped him be the clean-up batter aside from his natural genius of baseball, Abe has also stated that he has a strong throwing arm, but due to his size, he is physically incapable of hitting homeruns.
- The Rival: To Hanai. He doesn't realize/notice, though he does envy Hanai's height.
- Spiky Hair: Has this in season one, gets a haircut before season 2.
- Tempting Fate: His claim that he has never seen a pitch he couldn't hit by the end of the game may appear to be this, but it is averted. As of 2012 his hit streak is still intact.
- Too Much Information: Most of the things he says if not related to baseball.
- Translator Buddy: Sometimes for Mihashi and Abe.
- Weak, but Skilled: He's the smallest member of the team, so he can't score alone.
- You Keep Using That Word: And he uses it strictly.
- Youthful Freckles
- Chaste Hero: Like Abe, he doesn't have erotic fantasies, he's never fallen in love and if he got a girlfriend, he would like to hold her hand (to which his teammates respond: 'So cute...').
- The Generic Guy: Probably the least remarkable of the team members. His lack of quirks occasionally becomes a quirk for itself, when he is the only guy (or along with Abe) who isn't ticklish, doesn't have erotic fantasies, etc.
- Holding Hands: What he'd like to do if he ever gets a girlfriend.
- Real Men Cook: He loves to cook ever since he was in middle school. Recently, he is interested in baking and Japanese-like cuisine.
Position: Left Fielder , Third Baseman (vs Bijoudai-Sayama After Abe's injury)
Voiced by: Sumi Ken'ichirou (JP), Jean Luc Hester (EN)
- All Love Is Unrequited: He has a crush on Chiyo who has a crush on Abe.
- Butt Monkey: Apart from the fanon Kusoleft (crappy left field) thing he has going on for fumbling an easy catch, he's also been mentioned to be pretty shaky at batting and worried that Nishihiro is catching up to him. Oki straight up says that the two of them are the worst at batting on the team discounting Mihashi. And since Nishihiro is smart and serious and Mihashi is the ace pitcher, and Mizutani possesses none of these attributes but has a slightly dorky personality, he really is the last in coolness order of the team.
- In-Series Nickname: "Kuso Lefto" by Abe. He hopes to switch it to "Nice Batting".
- The Slacker: For this team standards, anyway.
Position: Center Fielder, Third Baseman(vs Sakitama)
Voiced by: Jun Fukuyama (JP), Chris Burnett (EN)
- Covert Pervert: Has the most hardcore fantasies of the group.
- Deadpan Snarker: Sometimes. Mostly around the Mihashi & Abe duo, Hamada or Mizutani.
- I Am Not Left-Handed: Is actually a switch hitter.
- Only Sane Man: He's "used to" Mihashi and Tajima.
- Youthful Freckles: Word of God states they're intended to be pimple scars, but fans assumed they were freckles.
Position: Right Fielder, Center Fielder(vs Sakitama)
Voiced by: Kissho Taniyama (JP), Joel McDonald (EN)
- Always Someone Better: Tajima is this to him.
- Compressed Vice: Starts out as a misogynist, a trait that quickly disappears (or at least his view that women couldn't be badasses gets corrected). Although to be fair to him, many people reacts to the fact of Momokan being a female coach with suspicion at least.
- Embarrassing First Name: his first name is Azusa, which is more common as a girl's name. He even makes his mom call him by his last name!
- Gender-Blender Name: Azusa is more traditionally a girl's name.
- Heterosexual Life-Partners: With Tajima.
- Hot for Teacher: Sorta.
- Has an "English teacher" fetish.
- Appears to have a slight crush on Momokan, though she isn't technically a teacher.
- Jerkass: Upon introduction.
- One Head Taller: Is a full head and then some taller than Tajima. His astounding height for a first year makes him not feel intimidated by the other high schoolers at the drawing for the summer tournament because he was so tall, standing taller than most players; both older and younger.
- The Captain
- Team Dad: Especially evident in his interactions with Mihashi.
- Unknown Rival: To Tajima, who has no idea that Hanai views him as Always Someone Better. Though as the time passes, Tajima starts to acknowledge his abilities more and each becomes a friendly version of The Rival to another.
- Younger Than They Look: His height and build makes him look more like a second or third year when he's actually a first year; however, he is one of the oldest members on the team.
Position: Third base coach, Reserve Left Fielder , Left Fielder (vs Bijoudai-Sayama After Abe's injury)
Voiced by: Ryohei Kimura (JP), Scott Hinze (EN)
- Academic Athlete: So smart the other members call him 'sensei' and he never has to study for tests.
- The Generic Guy: If you see someone from Nishiura and can't identify them, it's probably him.
- The Hopeless Replacement: Subverted. He comes on in the Bijou match and strikes out twice.
- The Smart Guy: He's the one to go to, when the dumber guys of the team need academic tutoring.
Momoe Maria, AKA Momokan
- Affectionate Nickname / In-Series Nickname: Her team calls her "Momokan" in the Japanese version and "Coach Mo" in the English dub.
- Buxom Is Better: She's very attractive and her enormous breasts are a factor.
- The Chessmaster
- Christmas Cake: Not there yet, but has some traits. Early in the series the boys thought 'unfitting' for a young woman to put all of her energy and savings to a baseball team and tried to 'rationalize' it by assuming she did it because she dated (the much older) Shiga-po. It wasn't true and Momokan really was Married to the Job.
- Manipulative Bastard: Manipulated Tajima into being backup catcher and first base after his hand injury so skillfully he doesn't even notice. She also tricked Abe into getting to know Mihashi better.
- Mission Control
- Most Common Superpower
- Tranquil Fury
- Tsurime Eyes
- The Ugly Guy's Hot Daughter
- Unusual Eyebrows: They curve downwards.
- All Love Is Unrequited: She has a crush on Abe, the guy who is THE least of the team to be interested in her.
- Cute Sports Club Manager
- Intergenerational Friendship: Apparently, with Shiga-po.
- Oblivious to Love: She doesn't seem to notice that Mizutani has a crush on her, or at least tactfully ignores it.
- She Cleans Up Nicely: At the cultural festival she wears a yukata with an apron. The boys of the team, who thought her 'mom-ish' in track suits, suddenly see her as a girl.
Tsuyoshi Shiga AKA Shiga-po
- Cool Teacher
- Dan Browning: pretty much anything he says.
- Intergenerational Friendship: with Chiyo
- Scary Shiny Glasses: Behind Momoe's back when she is discussing grades with the baseball club. It's clear that she's mostly discussing it because she's being coerced by him.
Hamada Yoshirou, AKA. Hama-chan
Voiced by: Jun Oosuka (JP), Jamie Mc Gonnigal (EN)
- Affectionate Nickname: Mihashi calls him "Shuu-chan".
- Friendly Rivalry: With Mihashi.
- Sand In My Eyes
- Tsurime Eyes
- David Versus Goliath: To Nishiura. Tousei being the previous champion compared to Nishiura's freshmen players.
- Graceful Losers: They even give Nishiura the thousand paper cranes their managers made them.
Voiced by: Eiji Hanawa (JP), Jeff Johnson (EN)
- Distracted by the Sexy: Strangely enough the only one in the series to be affected by Momoe's assets.
- Like an Old Married Couple: Riou says this about him and Junta in the manga.
- Nice Guy
Voiced by: Noriaki Sugiyama (JP), Drew Wall (EN)
- Like an Old Married Couple: Riou says this about him and Junta in the manga.
- The Tell: Makes distinctive motions when he's pitching and when he's picking off.
- Book Dumb: One of the reasons his brother did not recruit him for Bijoudai Sayama.
- But Not Too Foreign
- Cannot Spit It Out: Has a lot he wants to ask Tajima, but can't get the words out. Settles for his e-mail address instead.
- Defeat Means Friendship: Asks Tajima for his email address after Nishiura beats Tosei. A later chapter shows them meeting up and chatting.
- Theme Naming: Named after Rio de Janeiro
Position: Backup Pitcher (former), Pitcher (current)
Voiced by: Masaya Matsukaze (JP), Kevin M Connolly (EN)
- The Ace: Helped raise Musashino from a no-name team to finalists in the prefectural tournament.
- All Love Is Unrequited: Has a not-so-secret crush on Suzune.
- Character Development: Has changed dramatically from his middle-school jerk days to his current self, though Abe has yet to forgive him.
- Jerk Jock: In middle school.
- Reformed, but Rejected: Offers Abe an apology for his jerk behavior after the ARC game, but Abe is not placated.
- The South Paw
- Tsurime Eyes
Voiced by: Kiyotaka Furushima (JP), Daniel Katsük (EN)
Voiced by: Makoto Ishii (JP), Jason Liebrecht (EN)
- Always Someone Better: Muses later in the manga that he gave up trying at baseball when he saw how good Haruna was.
- Nice Guy
Position: Third Baseman
Voiced by: Kenji Takahashi (JP), Jerry Jewell (EN)
- Beast and Beauty: Dating the hot Suzune.
- Foil: to the Nishiura team and battery: Nishiura is a motivated team and Abe is a great pitch-caller, and Mihashi is passionate about pitching. On the other hand, the Sakitama team is so relaxed you never even see their coach. Daichi is not very good at being a catcher, and Ichihara is not that attached to being pitcher.
Position: Right Fielder (former), Pitcher(current)
Voiced by: Hisafumi Oda (JP)
Voiced by: Fukuhara Kouhei (JP)
- Flaw Exploitation: They exploit the hell out of Abe's pitch selection, and then they figure out Momokan's signs.
- One-Gender School: It's a boys' school.
Voiced by: Higuchi Tomoyuki (JP)
- Cheaters Never Prosper: Subverted. While his deeds are never outright exposed, the resulting guilt leads him to quit playing baseball after high school.
- Crippling the Competition: Done on Roka's orders to make things easier for Bijoudai.
- Ordered to Cheat: Only got his catcher position by obeying Roka's orders to injure other players.
- Unnecessary Roughness: How he injured opposing team players.
Voiced by: Kenji Hamada (JP)