Nobuyuki Kai (Japanese: (かい) 信行 (のぶゆき) Kai Nobuyuki) is a third-year student from Nekoma High. He is the boys' volleyball team's vice-captain and a wing spiker. As of 2021, Kai is a gardener and arborist[1]


Kai has jet black hair shaved into a buzzcut, somewhat thick eyebrows, and full lips. His eyes are heavy lidded, giving him a relaxed and approachable appearance. Whenever shown, he's usually beside Yaku or not too far behind him. He wears the jersey number 2.


Kai is a calm, collected, and peaceful person who is mostly in the background, giving him the role as Nekoma's vice captain. He doesn't talk much, but when he does, he's always polite. He's a very calm person in general.


Kai joined the Nekoma volleyball club in his first year, along with Yaku and Kuroo. He is shown to have put up with their squabbling, and when the first years were asked to state their goals in the club, he went along with what they said, which was to dominate nationals.


Karasuno High Team Formation Arc

Kai is introduced along with the rest of the Nekoma volleyball club during the practice match with Karasuno. During the match, he appears to face off with Daichi in being solid receivers but the two seem to become friends after the match.

Tokyo Expedition Arc

Kai mostly appears during the practice matches.

Spring High Preliminary Arc

Nekoma vs. Fukurōdani

Kai participates in the match between Nekoma and Fukurōdani.

Nekoma vs. Nohebi

Kai plays with Nekoma against Nohebi. When Yaku injures his ankle, Kai is shown being concerned but follows Kuroo's lead that they should continue to push through and do everything they can to win the last spot to represent Tokyo for the Spring Tournament.

Tokyo Nationals Arc

Nekoma vs. Kiyokawa

Kai is seen being able to get solid receives against Kiyokawa's ace.

Nekoma vs. Sarukawa

With the rest of the team, Kai tries to help protect Kenma from Sarukawa's attempts to bring down the Nekoma setter. He follows Kenma's instructions on which receives would be best for the sets he needs and is seen landing a few spikes throughout the second set. When Nekoma wins the game, Kai celebrates along with his teammates.

Nekoma vs. Karasuno

For majority of the first and second set, Kai is mostly seen taking part in receives and blocking. At the end of the second set, Kai is subbed out for Inuoka to be subbed in. Kai would return to the game at the start of the third set and would right away be the one to receives Kageyama's second serve.

Kai comes out of the game in the third set to Inuoka would go in again. Kai would finally compliment Inuoka's receives after having held back from doing so during the second set. He is subbed back into the game later on. Kai would attempt to save the ball when Kenma was unable to make the set because of the sweat covering the ball but was unable to reach it. After the teams shake hands, Kai would voice his gratitude for having gotten to play the last three years with Kuroo and Yaku, causing the two to burst into tears.

Final Arc

Kai's final appearance of the series is when he reunites with his former teammates at Kenma's house. After high school, Kai became a gardener and arborist.


High School Statistics
Game Sense

Not much of his abilities have been shown so far, but Kai appears to be a stable player like the rest of the team. He is flexible and very good at receiving.

Jumping Reach: 309 cm


Nekoma High

He has a good relationship with his teammates and gets along with everyone, especially Kuroo and Yaku.

Morisuke Yaku and Tetsurō Kuroo

Kai became fast friends with the two during their first years. They joined the volleyball club together and were often with one another, though Yaku and Kuroo would argue with each other all the time.


  • Favorite Food: Sea grapes
  • Current Concern: He does have some trivial concerns, but he figures that as long as you're alive, things will work themselves out one way or another.
  • His star sign is Aries.
  • In Haikyuu's first popularity poll, Kai placed 34th with 324 votes.[2] He did not rank in the second poll.[3]
  • Nomenclature:
    • Nobuyuki (信行)
      • 信 - Trust
      • 行 - Go
    • Kai (海) - Sea


  • "Have you guys already decided you're joining the volleyball club? If so, I look forward to working with the two of you for the next three years." (to Yaku and Kuroo, Volume 23 Chapter 200)
  • ""There's not many people out there who'd believe 100% that they're the ones to win." Maybe "belief' isn't quite the right word here. There are people who are crazy about victory. (Volume 37 Chapter 327)


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