|Seidou High School - No. 4|
|Bats: Right||Throws: Right|
|Nickname||Lucky Boy (ラッキーボーイ) |
|Age||15 (debut) |
|Date of birth||1 March|
|Place of birth||Kanagawa Prefecture|
|Weight||50 kg (110 lbs)|
|Education||1st Year High School (debut) |
2nd Year High School
|Class||1-B (former) |
|Skills||lightning fast easily adaptable bat control|
|Voice Actor||Hanae Natsuki|
|“||The Pinch-Hitter is me!||”|
— Haruichi to his teammates
Kominato Haruichi is a student of Seidou High School and the younger brother of Kominato Ryousuke. He is the roommate of Maezono Kenta and freshman, Mogami Takeshi. He plays second baseman and is one-half of the baseball team's Keystone Duo. He is also a close friend of Sawamura Eijun and Furuya Satoru.
Haruichi is a short, small framed teen with pink hair. His eyes are hidden by his bangs, only appearing during dramatic moments such as batting.
He is considered to be cute by his female classmates, his appearance being likened to a girl.
In Act II in the manga, Haruichi cut his front bangs after the Komadai match. His eyes are now easily seen.
Born in the Kanagawa Prefecture, he is a very calm and quiet person, often acting as the tsukkomi to Sawamura’s boke. He is shy by nature but has a habit of saying things bluntly and often praises either Furuya or Sawamura, causing the two to compete against each other frequently.
He plays reserve in the first-string team and occasionally feels envious of Sawamura and Furuya for being able to play in a match. He is rather small in comparison to the other boys and it has been noted that he looks a bit like a girl. He is easily embarrassed, especially when praised.
Haruichi's relationship with his brother is slightly strained because they play the same position, but he still admires the elder to no end. Though reserved, he is highly ambitious and aims to take his brother’s position. When he was a child, their relationship was closer, with Ryousuke often protecting him from bullies.
|“||I've been using a wooden bat at practice too so I know for a fact that if the ball is off the sweet spot even a little, it just won't fly.||”|
— Miyuki about Haruichi..
One of the most unique things about Haruichi is that unlike virtually every high school baseball player, he uses a wooden bat instead of a lighter metallic bat. He thought that in order to catch up to his older brother, he has to use the heavier, more difficult to master wooden bat. Haruichi is a naturally talented, all-rounder baseball player. Rei once said that his ability in baseball actually exceeds that of his older brother’s, also a talented contact hitter and a second baseman himself. He started out playing as a pinch hitter during the Summer Tournament and was later promoted to 3rd in the batting line-up, becoming one of the three-hole, starting from the second round of the Fall Tournament. He has held on to the position until the Spring Tournament of his 2nd year. After the Spring Tournament, he now bats 2nd in the lineup.
Despite his small stature and frail appearance, he has pinpoint precision while batting the ball. This makes Haruichi a skillful contact hitter, able to hit it as wide and as far as he pleases, and control where the ball lands and the fact that he uses a wooden bat make his skills even more impressive. Also extremely talented at defense, Harruichi is able to catch a ball in the air and throw it while still floating.
He is noted to have sharp baseball senses, able to decide in a split second where to hit the ball, what to watch for, and when to steal. As such, Haruichi is capable of pulling off fine plays that contributed greatly to Seidou in critical situations. For instance, in the 9th inning of Final of the Fall Tournament, Haruichi pulled off a series of consecutive fine plays that include landing a clean hit on Sanada's shuuto, stealing 2nd base and most significantly, feinting a squeeze to home plate to distract Yakushi's fielders allowing Miyuki to make it safely to 2nd base with his risky stealing attempt, all happening at 2 outs where one error could have immediately cost Seidou the match.
One of the thing he lacks is stamina, which he works hard on improving. Despite the fact that Haruichi has managed to hit a homerun once using a wooden bat, it has been repeatedly mentioned that he may lack power due to his small frame and also because the wooden bat is much heavier than a metal bat. To mitigate this weakness, Coach Ochiai ordered him to use a metal batin the intrasquad and Semifinal game during the Fall Tournament; however, after unsuccessful attempts in both games, Haruichi later refuses to use a metal bat again and decided to stick to his own style. His weakness resurfaced during the Spring Senbatsu where he was said to have less success in the National-level Tournament. After the loss to Ichidaisan High in the Spring Tournament, Haruichi is determined to improve the speed of his swing to make up for his small stature and has been practicing tee batting from all different types of difficult positions.
Note that this data is based on the official guidebook!
After Summer Tournament (89th National HS Baseball Championship Qualifiers), batting average is .571
- Haruichi ranked 4th in the first Official popularity poll. 
- Because he acknowledges Sawamura's talent, he sometimes says pretty harsh things to him.
- Along with Sawamura and Furuya he had been a member of the 1st string since his 1st year of high school, wearing jersey number 19 during the Summer tournament.
- In the newly formed Seidou team he began batting second like his brother, Ryosuke. But because of the new team's lack of batting power, he was moved to batting third, making him part of the clean up batters.
- Haruichi uses a wooden bat, that is more difficult to use and needs more strength than a metal bat. Despite that, he holds the best batting average (BA) of both the old and new Seidou team, with an avg of 1.000 and .512 BA.
- In his first tournament (summer tournament) he played as a pinch hitter, batting 4 of 4 with a perfect avg of 1.000.
- In Diamond no B!! Haruichi is a flutist who can summon monsters.
- Rankings from the guidebook:
- Favorite Food: Cream Stew 
- Favorite Subject: Modern National Language 
- Hobbies: TV games (action and combat) 
- During his year's 1st-Year vs Upperclassmen intrasquad game, Haruichi can be seen playing a Nintendo 3DS as he waited for his turn to play. 
- Kominato (小湊) - Small Encounter
- Haruichi (春市) - Spring City
- "The Pinch-Hitter is me!" 
- "Relax! Relax! If you try to force it, you won't be able to bat!" - to Sawamura
- "They both acknowledge each other, and they’re both aiming for the top together. That’s why they have such a good rivalry." - about Sawamura and Furuya
- "Harucchi's gone completely wild! Koshien has changed Harucchi. The Harucchi I knew is no longer here!" - Sawamura
- "I'm not going to wish for much. Only to hit for sure all the pitches that I know I can hit."
|Seidou High School|
|Miyuki Kazuya • Maezono Kenta • Kuramochi Yōichi • Kawakami Norifumi • Asou Takeru • Nakata Ataru • Ono Hiroshi • Higasa Shōji • Seki Naomichi • Yamaguchi Ken • Kijima Rei • Kawashima Kengo • Shirasu Kenjirō • Mimura Ryōta • Watanabe Hisashi|
|Sawamura Eijun• Furuya Satoru • Kominato Haruichi• Kanemaru Shinji • Tōjō Hideaki • Kaneda Tadahiro|
|Yui Kaoru• Yūki Masashi • Okumura Kōshū• Mogami Takeshi • Asada Hirofumi • Seto Takuma • Kuki Yōhei
|Former players||Yūki Tetsuya • Tanba Kōichirō• Kominato Ryōsuke• Masuko Tōru• Isashiki Jun • Miyauchi Keisuke • Sakai Ichirō • Kadota Masaaki • Kusunoki Fumiya • Takigawa Chris Yū • Azuma Kiyokuni
|Managers||Fujiwara Takako • Umemoto Sachiko• Natsukawa Yui• Yoshikawa Haruno
|Staff||Kataoka Tesshin • Ochiai Hiromitsu • Takashima Rei • Kazuyoshi Oota|