Diamond no Ace Wiki
He has a bad mouth, but I have never seen anyone as passionate as him.
Maezono about Jun
Isashiki Jun
Seidou High School - No. 8
Center Fielder
Bats: Right Throws: Right
Kanji 伊佐敷 純
Nickname Beard-senpai (髭先輩 Hige-senpai)(by Sawamura)

Spitz-senpai (スピッツ先輩 Supittsu-senpai)(by Sawamura) Seidou's Spitz
Angry Demon-senpai (鬼ギレ先輩 Oni Gire-senpai) (by Sawamura

Gender Male
Age 17 (debut)

18 [1]

Date of birth 1 September
Place of birth Kanagawa Prefecture
Bloodtype A
Height 169 cm (5' 6.5")
Weight 63 kg (138 lbs)
Education 3rd Year High School (debut)

Seidou Alumnus [2]

Class 3-B
First Appearance
Manga Act I - Chapter 14
Anime S1 - Episode 6
Voice Actor Yuuki Ono

Isashiki Jun was the vice-captain and center fielder of the Seidou High School baseball team. He was formerly roommates with Kudou Yasushi, and after the third years' retirement, he was roommates with Sakai Ichirou and Kusunoki Fumiya.


So you aren’t only a thug that plays dirty, huh?”
Sawamura about Isashiki

Isashiki is the team's reliable 'older brother' figure and a mood maker who can raise the morale of the team even in a pinch. He often yells at people, regardless of it being in the middle of a match or during practice, and physically manhandles them from time to time not unlike Kuramochi. He tends to lash out at people when the team is in trouble, though he does stay quiet until he is allowed to do so. Because of this, Isashiki appears hotheaded and intimidating, causing the underclassmen to fear him. Isashiki talks tall, but is modest inside and sincere about baseball. This is most evident when Maezono asks him about advice on batting, prompting Isashiki to reply that despite being a regular, he never once thought that he was a good baseball player. Isashiki also openly acknowledges his batchmate Yūki Tetsuya as someone who will always be better than him at baseball.

When the seniors first joined Seidou, Isashiki was one of the perkiest freshmen, immediately setting his sights on surpassing the famous Chris Yuu. Isashiki, along with the current senior regulars, were the freshmen who showed the most fighting spirit and who had the best potential to be part of the regulars.

Isashiki likes hanging out at Miyuki's room and often demands the latter to massage his feet for him. Furuya later takes on this role, though his habit of applying too much force often causes Isashiki to yell at him. Despite his rough exterior and loudmouth, Isashiki likes shoujo manga, a preference that was influenced by his sisters.

After their loss in the summer tournament, Isashiki, along with the rest of the seniors, had to retire and return to their normal high school life, a fact which his classmates find it amusing. Despite retiring, though, Isashiki and several other seniors occasionally visited the team to give advice, though it was often done in the form of yelling. However, it was done for their well-being as evidenced when Isashiki berated Kawakami for "letting the first-years walk all over him" and for being unable to move on from their loss.


Isashiki came from Ayakami Senior League. In his first year of high school, his desired position was pitcher, but he lacked ball control and couldn't hardly pitch strikes.[3] After the Tokyo Tournament and the selection of the new team, the coach moved him to the outfield due to his relaxed shoulders and strong throwing arm.[4]

Isashiki had the desire to be the best player on the team and eventually make it to Koushien. He ended up accepting the position as an outfielder instead of pitcher, and later became the main support as vice-captain to his rival Yūki once the latter was made captain. He was inspired by Yūki to improve his batting skills and to dedicate himself to becoming a good player, so much so that he held the center fielder position exclusively as a first-string player. He was also one of the most vocal of the third years when giving critical advice to his teammates: improving batting skills (Zono), performing as an outfielder (Sakai and Furuya), behavior and attitude (Sawamura and Kawakami), and leadership (Miyuki).

Because he was in the hospital at the time for back problems, Isashiki missed Sawamura's visit to Seidou and the resulting match against Azuma Kiyokuni.

Relationship with other characters[]

Yuuki Tetsuya[]

Yūki is strongly implied to be Isashiki's closest teammate. They initially had a rivalry during their first year but eventually became good friends. Yūki inspired Isashiki to work on his batting skills and work hard to improve. Isashiki sometimes compensates for Yūki's quiet demeanor by speaking up on his behalf, especially when he feels Yūki is not addressing team matters as vocally as a captain should. Despite their competitive relationship at the start, Isashiki cites Yūki as a man he will never beat "in a million years," though he refuses to repeat the sentence aloud.

Furuya Satoru[]

His personal massager. Isashiki often yells at Furuya (as he would any other underclassmen), but trusts him as a pitcher regardless.

Miyuki Kazuya[]

Isashiki often visits his room or asks him to analyze their opponents. While he has had initial doubts about Miyuki as the new captain, Isashiki ultimately trusts him to lead the team.

Azuma Kiyokuni[]

Isashiki holds Azuma in high regard and was in disbelief when he found out "someone like Sawamura" managed to strike him out. Despite being loud and informal most of the time, Isashiki speaks to Azuma respectfully (and at a normal volume) and still calls him Azuma-senpai. He was also the first to greet Azuma when he paid Seidou a visit before the match against Inashiro Industrial, and an uncharacteristically large smile was plastered on his face the whole time in place of his usual scowl.



Isashiki originally joined the team as a pitcher; however, because he lacked control, he was placed at center field. He can quickly throw balls from the outfield up to the catcher without even bouncing the ball. He is the only permanent outfielder because of his defensive skills.


He is one of Seidou's best hitters alongside Masuko, Yūki and Ryousuke and is known as a power hitter. Isashiki has no fixed batting pattern and hits at whatever opportunity he knows he can hit. Like Yūki, he spends most of his time practicing his batting. He looks up to their former senpai Azuma who is also a power hitter.

As the third batter in the three-hole, he is is generally the best all-around hitter on the team, often hitting for a high batting average but not necessarily very quickly. Part of his job is to reach base for the cleanup hitter and to help drive in baserunners himself. Hitters in the three-hole spot are best known for "keeping the inning alive."

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


  • Jun ranked 10th in the first Official character popularity poll. [5]
  • He has two sisters. One is two years older, the other one is six years.
  • Nomo Hideo was a pitcher that Jun admired when he was a first year and a pitcher.
  • Has respect for Azuma Kiyokuni.
  • Rankings from the guidebook:[6]
    • First at shoulder strength.
    • Second best in outfield defense
  • Favorite Food: Yakiniku[6]
  • Best Subject: Sports[6]
  • Hobby: Reading shoujo manga[6]
  • After graduating from high school, he attends a university in the Kansai region. [7]
  • He started baseball because he likes pro baseball.[6]

Name Etymology[]

  • Isashiki  (伊佐敷) - Applying Help
  • Jun (純) - Pure


  • "How can I get on base? How can I create a chance? How can I connect to the next batter? With this at every at-bat, I desperately get my teeth into the ball. It’s frustrating, but no matter how much I try there’s a great batter right behind me whom I’m no match for." - to Maezono about Yuuki Tetsuya
  • "Who are you calling a spitz?!" - to many people
  • "I don't know, I've never been to Koshien. If you wanna find out, go there yourself and learn it firsthand, moron!" - to Sawamura [8]
  • "On top of his bad mouth, he looks fierce. But I have never seen anyone as passionate as him. You're the best, Jun-san!" - Maezono[6]



  1. Act I - Chapter 220
  2. Act I - Chapter 412
  3. Act I - Chapter 146
  4. Act I - Chapter 147
  5. Act II - Chapter 51
  6. 6.0 6.1 6.2 6.3 6.4 6.5 Official Guide Book - Omote
  7. Act I - Epilogue 3 "Brand New Day"
  8. Act I - Chapter 201