|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|
|Height||164 cm (5'4)|
|Weight||50 kg (110 lbs)|
|Education||1st Year High School (debut) |
2nd Year High School
|Class||1-B (former) |
|Skills||High ball contact, adaptable bat control, batting eye|
|Voice Actor||Hanae Natsuki|
|“||I want you to use your bat, to become Seido's booster rocket!||”|
— Kataoka Tesshin to Haruichi
Kominato Haruichi is a second year 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, usually only appearing during dramatic moments such as batting. He is considered to be cute by his female classmates as his appearance is often likened to a girl's.
In Act II, Haruichi cut his front bangs after the Komadai match, so his pink eyes are now visible. Occasionally when annoyed or devious, he adopts a closed-eyed appearance much like his brother, Ryousuke.
Haruichi is very calm and quiet, 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 Furuya and Sawamura, causing the two to compete against each other.
In Act I, he played reserve for the first string team and occasionally felt envious of Sawamura and Furuya for being able to play in a match. He was sent in as a pinch hitter several times during the tournament though, proving himself to be a reliable hitter. He is easily embarrassed and blushes hard when praised.
Haruichi's relationship with his older brother, Kominato Ryōsuke, is slightly strained as they play the same position, but Haruichi still admires him to no end. Though reserved, Haruichi is highly ambitious and aimed to take his brother’s position. When he was a child, they had a closer relationship, Ryōsuke often protecting Haruichi 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 metal bat. He believed that in order to catch up to his older brother, he had to use the heavier, more difficult wooden bat.
Haruichi is a naturally talented, all-rounder baseball player in both batting and fielding. Kijima Rei once said that his ability in baseball actually exceeded that of his older brother’s, who is also a talented contact hitter and a second baseman himself. He also do things that are similar to his brother, and not just in behavior but also in skills and technique. Haruichi started out as a pinch hitter during the Summer Tournament. Once the new team was formed, he was later promoted to third in the batting line-up, becoming the three-hole starting from the second round of the Fall Tournament. He held on to the position until the Spring Tournament of his second year. After the Spring Tournament, he now bats second in the lineup.
Despite his small stature and innocent appearance, Haruichi has pinpoint precision while batting. This makes him a skillful contact hitter, being able to hit it as wide and as far as he pleases, and control where the ball lands. The fact that he uses a wooden bat make his skills even more impressive. Haruichi is also extremely talented at defense, able to catch a ball in the air and throw it while still moving.
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 help his team greatly in critical situations. For instance, in the ninth inning of Final of the Fall Tournament, Haruichi pulled off a series of consecutive incredible plays that include landing a clean hit on Sanada Shunpei's Shuuto, stealing second base, and most significantly, feinting a squeeze to home plate to distract Yakushi High School's fielders despite there being two outs, allowing Miyuki to make it safely to second base with his risky stealing attempt.
One thing Haruichi lacks is stamina, which he works hard on improving. Despite the fact that Haruichi was able to hit a home run once using a wooden bat, it has been repeatedly stated that he may lack power due to his small frame and the wooden bat's heavier weight. To mitigate this weakness, Coach Ochiai Hiromitsu ordered him to use a metal bat during the intrasquad and semifinal of the Fall Tournament; however, after unsuccessful attempts in both games, Haruichi later refused 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 Hauichi acknowledges Sawamura's talent, Haruichi sometimes says pretty harsh things to him.
- Along with Sawamura and Furuya, Haruichi had been a member of the first string since his first 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. He was eventually moved back to the two-hole for the Summer Tournament.
- Haruichi uses a wooden bat, which 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 four of four 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 when Haruichi cut his bangs
- "I'm not going to wish for much. Only to hit all the pitches for sure that I know I can hit."
- "He's a little devil./ What a scary guy." - Chris to Haruichi
- "He kept the bat head back and sent an inside pitch all the way to the right field?! That's some serious master level bat control."- Yui to Haruichi
- " 'Hit the ball back dutifully', huh? In a match, this is the most difficult thing to accomplish." - Kataoka to Haruichi
- "I'll do it too!" - about Ryousuke
|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|
|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|