Haikyū!! Wiki
Haikyū!! Wiki

Sadayuki Mizoguchi (Japanese: 溝口 (みぞぐち) 貞幸 (さだゆき) Mizoguchi Sadayuki) is the coach of the Aoba Johsai High boys' volleyball team.


He appears to be around the thirties. He has short blond hair and eyebrows. He is most often seen wearing the Aoba Johsai tracksuit.


He takes the matches and practices very seriously and is often seen yelling at the players, even over little things. He also seems to be respectful around other adults, especially Irihata.



Karasuno High Team Formation Arc

Mizoguchi first appears during the practice match between Aoba Johsai and Karasuno. After Irihata has revealed to the team that Kageyama has been adjusting his sets so the spikers have an easier ball to hit, Mizoguchi remarks how it seemed like a drawback that Kageyama hadn't accepted Irihata's invitation to join Aoba Johsai.

Interhigh Arc

Mizoguchi and the team are present to watch part of Karasuno's match against Date Tech. He comments how Date Tech's read blocking is problematic for their opponents but, like others, is aware that Karasuno's freak quick attack is able to change things to Karasuno's favor.

When Seijoh and Karasuno eventually play one another, Mizoguchi steps back from coaching as he and Irihata allow the players to lead themselves or follow Oikawa's leadership.

Spring High Preliminary Arc

Mizoguchi is excited to see the team ready to play against Karasuno again but would express surprise when he hears Iwaizumi, Matsukawa, and Hanamaki state that they have complete trust in Oikawa to lead them to victory.

At the end of the first set, Mizoguchi would share in everyone's shock when Kyōtani unintentionally lost the set for Aoba Johsai by putting too much power into his spike. His frustration with the wing spiker would continue throughout the second set when Kyōtani would continue to be reckless in his plays and his refusal to try things like feint shots because they did not have the same satisfaction as a powerful spike. When Sugawara is subbed into the match and begins aiming his serves at Kyōtani to make him late to attack, Mizoguchi is quick to figure out that this is being done intentionally since Kyōtani was a big threat to Karasuno.


Aoba Johsai High

Mizoguchi yelling at Kunimi

Mizoguchi seems to nitpick Kunimi more than the others players; most likely from seeing that the first-year tends to put minimal effort into his plays. Mizoguchi also tries to get Kyōtani to be more of a team player when he rejoins the team but is frustrated when he would refuse to use any other attacks besides powerful spikes; which tended to backfire at critical moments. While he is not shown having much interaction with the rest of the team, Mizoguchi appears trust Oikawa's leadership and strategy as he and Irihata allow the setter and the rest of the players to lead themselves without needing much help from their coaches.



  • Current Concern: Sometimes he'll catch himself saying "Kids these days..." and it's like he can feel his own descent into middle age[1].
  • Nomenclature
    • Sadayuki (貞幸)
      • 貞 - Chastity
      • 幸 - Fortune
    • Mizoguchi (溝口) - Gutter Mouth