Diamond no Ace Wiki
Kominato Ryōsuke
Seidou High School - No. 4
Second Baseman
Bats: Left Throws: Right
Kanji 小湊 亮介
Nickname Ryou-chan (亮ちゃん) (by family)

Ryou-san (亮さん) (by kouhai)
Ani-san (兄さん) (by Sawamura)
Onii-san (お兄さん) (by Sawamura)

Gender Male
Age 18

19 [1]

Date of birth 6 April
Place of birth Kanagawa Prefecture
Bloodtype B
Height 162 cm
Weight 55 kg (121 lbs)
Education 3rd Year High School (debut)

Seidou Alumnus [2]

Class 3-B
First Appearance
Anime S1 - Episode 4
Voice Actor Nobuhiko Okamoto
If you don’t want to lose to guys with bigger bodies, you should just train as many times harder.
Ryousuke to Kijima

Kominato Ryousuke was a student of Seidou High School and is the older brother of Kominato Haruichi. He was formerly the baseball team's second baseman and one half of Seidou's Keystone Duo.


Ryousuke is quite confident in himself. He is strict to others but he trains himself much more. He is especially strict to his younger brother among all of the kouhais. He looks gentle but has quite a sharp tongue. [3]

Yet he is lighthearted towards his fellow third years and also a very reliable and considerate classmate as well. He is also very strong willed as he would push himself more and more if that took them closer to Nationals and he has a dark sense of humor.


Kominato Haruichi

Haruichi is Ryousuke's younger brother. While Ryousuke often expressed that being an elder brother was troublesome, he still cares for Haruichi. Although their relationship seems strained at first with Ryousuke mocking Haruichi for his lack of stamina, he starts helping Haruichi from time to time as the series progresses. Ryousuke comes to entrust Haruichi with his position during the Inashiro and Seidou match, and has occasionally implied that Haruichi may progress far more in baseball than him in the future. When they were younger, it is revealed that the Kominato brothers were much closer. Ryousuke was very protective of Haruichi, defending him from bullies even at his own expense.

Kuramochi Youichi

They are considered two of the best middle infielders in the area. Kuramochi and Ryousuke share a close bond, having a close understanding of what each other is doing when fielding. Despite routinely insulting Kuramochi in his first year, Ryousuke came to trust him deeply as his partner in baseball. Kuramochi was the first person to notice Ryousuke's injured right leg before the Inashiro and Seidou match; in turn, Ryousuke allowed himself to be called out by Kuramochi despite having hidden his injury from everyone else on the team, proving the amount of trust he places in his "year-long partner." They are revealed to still be in touch even after Ryousuke has graduated, hinting that they have a close relationship even outside the field.


Ryousuke is quite confident in himself, being nothing but self-assured on the field, but on the other hand, he puts more effort than anyone during practice and games. Together with Kuramochi, they are considered to be two of the best middle infielders in the area.

Player Statistics

This data is based on the official guidebook, it will only be changed if there is an official update!

Player Statistics
Note that just because a character said something about another characters improvements is not considered an official update!
You are free to write about the characters improvements in the Skills section above!
Physical Strength
Mental Strength


  • Ryousuke ranked 7th in the first Official characters popularity poll, moving down from 6th place in the primary online voting result. [4]
  • He has respect for his family
  • He likes horror movies and ghost stories
  • Rankings from the guidebook: [3]
    • Defense:
      • He ranks first in Glove handling
      • He ranks second in Infield defense
    • Batting:
      • He has the best batting eye
      • He ranks second at bunting
      • He ranks fifth at batting contact.
  • Favorite Food: Spicy foods, Curry (spicy) [3]
  • Favorite Subject: Math [3]
  • According to Terajima's Twitter:
    • Ryousuke also cut his hair.[5]
      • His new look was revealed in Ch 204 of Act II. [6]
    • He is bad at video games.
    • He started playing baseball because his father is a Yakult Swallows fan.
  • He attended Youko Junior High

Name Etymology

  • Kominato (小湊) - Small Encounter
  • Ryousuke (亮介) - Meditating Brightness


  • "During the game, don't just help Sawamura, get yourself ready too. You got switched in the first game, the coach keeps using those in good condition." - to Haruichi[7]
  • "I hope you smacked them a good one?" - to Haruichi[8]
  • "I probably can make Haruichi switch with me and no one will suspect!"[9]
  • "Don't try and make excuses about talent. It's about how much you're putting in. As for me, I'm always think "Eat shit" when I play." - to Kijima[10]
  • "What a greedy guy." - to Haruichi[11]
  • "He's invinsible. If he manages to get on base, that is." - about Kuramochi[12]
  • "Hiding his wicked tongue behind a smile" - Guidebook [3]



  1. Act II - Chapter 15
  2. Act I - Chapter 412
  3. 3.0 3.1 3.2 3.3 3.4 Official Guide Book - Omote
  4. Act II - Chapter 51
  5. https://twitter.com/diaace_official/status/717395343822835712
  6. Act II Ch 204
  7. Act I - Chapter 72
  8. Act I - Chapter 94
  9. Act I - Chapter 258
  10. Act I - Chapter 320
  11. Act I - Chapter 366
  12. Act I - Chapter 370