Diamond no Ace Wiki
Yui Kaoru
Yui Kaoru anime
Seidou High School - No. 19
Bats: Left Throws: Right
Kanji 由井 薫
Gender Male
Age 15 (debut)
Date of birth 27 April
Place of birth Tokyo
Education 1st Year High School
Style power hitter
Skills Resilient player
First Appearance
Manga Act II - Chapter 1
Voice Actor Murase Ayumu
You are a tough one!
Sawamura to Yui

Yui Kaoru is a first year student of Seidou High School and roommates with Furuya Satoru and Ono Hiroshi. He wears Seidou's No. 19 jersey for the Summer Tournament.


Yui is a short boy with light brown hair, thick eyebrows, big eyes, and is often seen wearing a smirk on his face.


Yui is a hard working first year with a competitive spirit and drive to improve. He is shown to be very determined, almost always offering to catch for Furuya or Sawamura when he's given the chance, and although he may be disheartened when denied, he takes it as a sign that he needs to work harder and prove himself to his upperclassmen. He is truly a team player, as although he wants to be a catcher, he doesn't mind being a pinch hitter if it's for the good of the team. He values the time he gets to play, and is self critical.


He was the unshakable starting catcher in the Mamiya Senior League, and is a known prodigy in his generation who captained the Japanese Representative team in the Little League World Series.

Act II[]

Arriving early at Seidou, Yui has a brief encounter with Okumura, Seto and Yuuki, after which he heads to the dorms. In the dorm room, he tells Furuya to feel free to call him anytime Furuya feels needs a catcher; Yui also admits that he's been interested in seeing Furuya's pitches for the longest time.

Spring Tournament[]

Yui watches Seidou's third round match against Eigen from the bleachers. He makes it to the first string and observes how Miyuki leads Furuya in the fourth round. Later at the Seidou dorm, Sawamura asks Miyuki to catch for him but Yui is quick to volunteer instead as he found it difficult to catch Sawamura's pitches in the bullpen.

After Seidou's quarterfinals match victory, Yui offers to catch for Furuya knowing that Furuya isn't satisfied pitching in the quarterfinals.[2] Furuya declines Yui, preferring to have Miyuki catch for him instead, to Yui's surprise. Furuya says that he wants to pitch at ease without holding back. Yui then feels frustrated, clenching his fists while thinking back during practice that he's had a hard time catching Furuya's pitches.[3]

Relationship with other characters[]

Furuya Satoru[]

Yui ace3ep9

He highly respects[4] the former ace of the team, who is also his roommate, and eagerly wants to catch for him because he's interested in seeing Furuya's pitches up close.

Sawamura Eijun[]

He is also interested in Sawamura's pitches and wants to catch for him as soon as an opportunity arises because he had troubles catching his pitches the first time.[5]


Yui actiiss3 ep8

Yui has batting power, good running, and an excellent shoulder. He is not as naturally gifted as Miyuki or Okumura when it comes to pure catching skills; however, with good communication and a strong will, Yui is determined that his hard work would be able to make up for what he lacks.

Yui and Masashi seems to have good stamina for a first year and they were able to keep up with their older peers practice regimen since the start of their enrollment in Seidou, one of the reasons why both were added to the first string early.


  • Yui is one of the few freshmen who can easily scarf down breakfast and is always first.

Name Etymology[]

  • Yui (由井) - Well of Reason
  • Kaoru (薫) - Fragrant


  • "If they are serious about the national championship, they'll need this pitcher." - about Sawamura
  • "I can't help wondering just what kind of fastball he throws." - about Sawamura [6]


  1. Act II - Chapter 52
  2. Act II - Chapter 31
  3. Act II - Chapter 32
  4. Act II - Chapter 12
  5. Act II - Chapter 23
  6. Act II - Chapter 13