Diamond no Ace Wiki
Amahisa Kōsei
Amahisa Act 2
Ichidaisan High School - No. 1
Bats: Right Throws: Right
Kanji 天久 光聖
Nickname Genius (天才

Jīniasu) [1][2]

Gender Male
Age 16 (debut)

17 [3]

Date of birth 24 December
Place of birth Tokyo
Bloodtype B
Height 182 cm (5' 11.5")
Weight 70 kg (154 lbs)
Education 2nd Year High School (debut)

3rd Year High School (current)

Skills Slider
151 kph fastball
First Appearance
Manga Act I - Chapter 291
Anime S2 - Episode 19
Voice Actor Kimura Ryohei

Amahisa Kousei is a student of Sankou and the ace of Sankou's baseball team, succeeding Manaka Kaname.


Amahisa is a lean built teenage with a close shave. He has thick eyebrows and thick lips.


Amahisa is a confident and very talented pitcher who is not easily fazed even when faced with strong batters. He thinks a lot in a match, evaluating not only his opponents but also himself— his condition and pitching. He has a tendency to get himself preoccupied with batters that greatly interest him such as Todoroki Raichi, thus pays less attention to all others but this could have negative results. On the other hand, he has shown that he has respects for players from other teams such as Raichi and Sawamura who have impressed him.

He's regretted leaving the team after the 83rd Spring Koshien on a whim, and feels very grateful that the team had welcomed him back in the Fall. He is aware that others may still have something against him and thus, greatly desires to be truly accepted as a teammate. He claims to hate working hard but will practice hard in secret. He can also be tactless when speaking.


One year before the series starts, Amahisa was a first year pitcher at Ichidaisan. He was part of the team that won the Fall Tournament, eliminating Seidou High along the way. He and Ichidaisan reached the quarterfinals of the 83rd Spring Koshien.

After the team was eliminated from the Spring Koshien, however, Amahisa began to feel bored towards baseball. He felt he had no free time to do leisurely things or spend time with his girlfriend. He surprisingly quit the team before the summer of his second year of high school.

After Ichidaisan got eliminated in the West Tokyo Regional qualifiers for the 89th Summer Koshien and seeing his upperclassmen, especially Manaka, fail to reach their goal, Amahisa had a change of heart and requested to join the baseball team again. He knows that some members of the team may be unhappy with how selfish he has been, but he looks to gain their trust again through his pitching.

Act I[]

Fall Tournament[]

Amahisa is first seen in playing in the Third Round of the Fall Tournament, where he helps secure a ticket to the quarterfinals for his team. Sankou makes it past the quarter-finals, and Amahisa looks forward to his chance of revenge at Raichi, whom he has been eyeing all the while, when they face Yakushi High in the semi-finals.

He sees two of his teammates practicing late at night and thanks them for taking him back without a word after coming back. But his teammates say that he should thank the coach since it was Tahara who politely asked the team to forgive Amahisa for leaving. Amahisa is surprised to hear this then goes back to his room.[4]


Following Seidou and Seiko's semi-finals match-up, is Sankou's match against Yakushi. As Seiko clears the dugout, Amahisa sees a frustrated Tsune and asks how it feels when the teams loss is caused by himself, aggravating Tsune.

At game time, Amahisa pitches well against Yakushi High, taking a lead late into the game in his pitching duel with Sanada. In the eighth inning, he manages to strike out Raichi with runners in scoring position using his slider. However, he gives up the tying and winning runs to opposing pitcher Sanada, who hits Amahisa's fastball. Ichidaisan failed to reach Koshien for the second time in a row, getting eliminated by Yakushi once again.

Act II[]

Spring Tournament[]

In the third round of the tournament, Ichidaisan plays against Kawamura High. Amahisa uses his sharp breaking slider to strike out a batter, but didn't realize the game also ends with that. He expresses his discontent that the game has ended so fast because his teammates were scoring like crazy. His teammates are quite surprised with the remark but Amahisa brush it off saying it's a joke. His teammates though, think he's being serious.[5]

He watches Seidou High's match against Kasugaichi but soon left, losing interest in watching when at a decisive moment, Kasugaichi's battery gets cold feet instead of being aggressive.[6]


In the match against Niougakusha Ootsuki High, Amahisa doesn't give up runs but knows that he isn't performing well. The score is at a stalemate until the bottom of the fifth with Ichidai scoring two runs. Amahisa then steps up his game, raking up strikeouts with his Slider. From the fifth inning onwards, despite Niou's attempts of a counter-attack, Amahisa crushed Niou, not allowing a single runner reach second.[7]


Amahisa speaks to Sawamura.

In the semifinal against Seidou High, Amahisa gives up two runs at the top of the first. He eventually steps up his game, keeping Seidou's batters at bay with his Slider. His team supports him, scoring five runs in the bottom of the fifth. At the top of the ninth, Seidou managed to get back another run with Shirasu's infield grounder. Nonetheless, Amahisa retires Maezono preventing Seidou from tying the game. With the score at 5-3, Sankou advances to the Finals.

Following their match, he sees Sawamura and asks about a pitch the sophomore threw at his teamates. Sawamura expresses his annoyance at Amahisa's attitude, but Amahisa shrugs it off saying that they are only discussing baseball as pitchers.[8]

Relationship with other Characters[]

Manaka Kaname[]

Amahisa respects Manaka. He had previously quit the team but decided to return having seen Ichidaisan's defeat in the summer, and wanting revenge for Manaka.

Tahara Toshihiko[]

Amahisa seem to feel a sense of closeness towards his coach, calling him Toshi-chan.

Sawamura Eijun[]

After Sawamura demonstrated great relief pitching against Ichidaisan in the Spring Tournament, Amahisa has taken keen interests in Sawamura, most notably, he is particularly interested in learning more about Sawamura's Cutter. The pair exchanged LINE contacts and they have been sharing advice and experiences about pitching to one another since and seems to have developed a friendly-rival relationship with one another. Taking inspiration from Sawamura's Cutter, Amahisa came up with a new pitch that's a mix between a Slider and the Cutter known in the Major League Baseball as the **Slutter**. After Ichidai's defeat in the Summer tournament, he tells Sawamura how he's honored to have faced him in his last high school game.


Amahisa is an incredibly gifted pitcher in almost every aspect of pitching. He can locate his pitches to the corners of the zone easily and jokingly said to his coach that he can do that whenever he wants. Amahisa's velocity tops out at 151 kph in his 3rd year Summer Tournament, making him one of the few pitchers that can reach over the 150 kph velocity mark in the Nation[9]. On top of that, Amahisa possesses perhaps the best Slider in the series which is especially effective when used against a righty batter who borderline cannot touch his front-door Slider that appears as though it would hit them, only to move back into the zone for a strike. He also has a Curveball that he uses as an off-pace pitch to get batters off-balance and increase the effectiveness of his fastball. In an effort to make his Slider breaks less at the plate, Amahisa took inspiration from Sawamura's Cutter and came up with a new pitch called the Slutter. The breaking pitch is a hybrid of the Slider and a Cutter which makes it looks like a fastball midway to the plate but has a sharp vicious downward break at the plate like a vertical Slider.

Amahisa is noted to be a bit shaky in the early stage of a game where his breaking pitches could be erratic. However, once he has his engine running and his breaking pitches working, he can quickly closes the door on a game and becomes very difficult to hit off of. Amahisa could be very cocky and that historically has led to his downfall if he lets his impulses dictate his game; however, after sorting out his mental shortcomings, Amahisa has been able to consistently perform well and became one of the best pitchers in the Tokyo Prefecture.

In terms of batting, Amahisa isn't a great batter. His batting average is low but he's said to have a good knack for it like most pitchers are. He was able to read Miyuki x Furuya battery in the Spring Tournament SF and earn Ichidaisan the lead by hitting an RBI of his own off of a powerful Furuya's fastball.

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


  • He has a girlfriend.
  • He once withdrew from club activities immediately after 83rd Spring Koshien.
  • He is one of the only known pitchers in the series besides Tanba, Sawamura and Narumiya who struck out Raichi.
  • After the game with Seidou in the Spring Tournament, Amahisa pestered Sawamura for information of his Cutter. He went as far as forcing Sawamura to share his line contact and messaged him constantly throughout the off-season which annoyed Sawamura greatly.
  • Rankings from the guidebook: [10]
    • Amahisa's breaking balls have the best break.
  • Has respect for: Miyavi[10]
  • He can play the Guitar and Drums.[10]

Name Etymology[]

  • Amahisa (天久) - Long Heaven/Sky
  • Kousei (光聖)- Holy/Sacred Light



  1. Act II - Chapter 40
  2. Is alternatively read as Tensai
  3. Act I - Chapter 412
  4. S2 - Episode 30
  5. Act II - Chapter 15
  6. Act II - Chapter 29
  7. Act II - Chapter 31
  8. Act II - Chapter 46
  9. Act II - Chapter 173
  10. 10.0 10.1 10.2 Official Guide Book - Omote