Diamond no Ace Wiki
Mukai Taiyō
Teito High School - No. 1
Bats: Left Throws: Left
Kanji 向井 太陽
Gender Male
Age 15 (debut)

16 [1]

Date of birth 20 March
Place of birth Tokyo
Bloodtype O
Height 175 cm (5' 9")
Weight 63 kg (140.5 lbs)
Education 1st Year High School (debut)

2nd Year High School [2]

Style Southpaw, side-arm control pitcher
Skills Screwball
First Appearance
Manga Act I - Chapter 238
Anime S2 - Episode 4
Voice Actor Saito Soma
The number 1 pitcher of this generation is me!
Mukai in This Generation[3]

Mukai Taiyou is a student of Teito High School and the ace of its baseball team. He is a lefty sidearm pitcher and has debuted at the 89th Summer Koshien.


Mukai is a side-arm pitcher confident in his pitching skills and believes himself to be the number one pitcher of his generation. Pitching has been tremendously fun to him since middle school and even considers himself addicted to it.

Act I[]

Fall Tournament[]

In the first round of the Fall tournament, Teito High face against Seidou High. After Furuya strike out Kengo at the top of the first, Kengo praise Furuya and so does coach Okamoto. Mukai however, doesn't share the same opinion. Bottom of the first, Mukai utilizes the corners to strike out Kuramochi and successfully held Seidou scoreless up to the fourth. Due to the strong rain, the game was temporarily put on break before Teito's defense at the fifth inning. When the game resumed, Miyuki hits Mukai's pitch and runs all the way to second base.[4] Seidou however, has not scored despite being in the position to.

Bottom of the sixth and with two outs, Mukai walks Kuramochi. Haruichi hits the first pitch next, and Kuramochi sprints to third. Now with two outs, runners on first and third, Mukai will face Seidou's clean-up batters. He lures Maezono into hitting a high ball that results to a fly ball to third. Bottom of the seventh, with a runner on first for Seidou, Sawamura bunts to hopefully move the runner to second but fails.[5]

Bottom of the eighth, Mukai's pitch count has exceeded 120 but he strikes out Seidou's Higasa and Asou. He face Toujou next and wonders why Toujou is a fielder. Mukai had hoped that like they were in middle school, he and Toujou would square off again in High school. He gets a little irate that Toujou had allowed outsiders like Sawamura and Furuya to take over the mound. Toujou one-handedly swings his bat, hitting Mukai's pitch and the ball goes past second. Toujou gets on base, and determinedly looks at Mukai. Mukai gets annoyed as he thinks that even back in middle school, it was only Toujou who can hit his winning pitch.[6] Kuramochi is at-bat next and he bunts surprising Teitou. Kuramochi gets to second after Teitou makes an error in their defense while Tojou advances to third. Teito's battery decide to walk Haruichi, choosing to face Maezono instead. After a couple of throws, the count is 2B:2S. Maezono eventually hits the pitch and the runners get home. Seidou takes the lead at 1-3. Teito makes an effort to turn the game around at the last inning scoring one run, but Kawakami manage to successfully close the game despite the bases being loaded.

After the match, Kengo tells Mukai that their off season will be longer but Mukai disagree saying that it will be over in a flash, if they focus on polishing their skills.[7]

Act II[]

Spring Tournament[]

During the Spring Tournament quarter-finals, Teito High play against Ugumori High. At game time, Mukai and Kengo tries out their new style that's designed to decrease Mukai's pitch count, and their aggressive style has been effective against Ugumori's aggressive batters. At the bottom of the third, Teito scored a run giving them an early lead and at the top of the fifth, Mukai keeps his number of given up runs at zero.[8] Kengo follows suit hitting 2-RBIs.

Bottom of the eighth, two outs, runners on first and second, Mukai battles Umemiya. Mukai attacks aggressively, throwing fastballs to the inside that Umemiya fouls. Umemiya eventually makes contact with a pitch but a fine play from Teito's second baseman prevents Ugumori from scoring. And with the Ugumori team failing to score the next inning, Teito High advances to the semis.[9]


Finesse yet boldness, this unlikely combination is where the true worth of Mukai Taiyou's pitching lies.
Mine Fujio on Mukai's pitching
Mukai's vision of the strike zone.

Pitching: Mukai is a side-arm pitcher with excellent control of his pitches and he sees the strike zone as not only divided into 9 sections but in 3 dimensions, with depth.[10] He rarely throws meatballs, and finishes with a breaking ball. His pitches are difficult to hit widely making use of the zone corners, and batters get jammed by his low pitches.[11]

During the Spring Tournament, Mukai style changes as he pitches more aggressively, persistently attacking the inside more often rather than utilizing the zone corners. He throws mostly fastballs to keep his pitch count low and mix his Screwball at decisive moments.

Pitcher's Data[]

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

Pitcher's data
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!

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


  • Rankings from the guidebook: [12]
    • He ranks second in ball control (with You Shunshin ranking first).
  • Favorite food : Snack food [13]
  • Best subject : Math [13]
  • Hobby : Games, such as Winning Eleven and love simulations [12]
  • According to Terajima's twitter, the Mukai-Inui battery are very devoted to their skincare.

Name Etymology[]

  • Mukai (向井) - Direction Well
  • Taiyou (太陽) - Sun



  1. Act I - Chapter 412
  2. Act II - Chapter 1
  3. Act I - Chapter 238
  4. Act I - Chapter 246
  5. Act I - Chapter 251
  6. Act I - Chapter 253
  7. Act I - Chapter 256
  8. Act II - Chapter 25
  9. Act II - Chapter 26
  10. Act I - Chapter 240
  11. A meatball is an easy pitch right down the middle of the plate.
  12. 12.0 12.1 Official Guide Book - Omote
  13. 13.0 13.1 Official Illustration Book