Haikyū!! Wiki
Haikyū!! Wiki

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 lidded, giving him a relaxed and approachable appearance. He wears the jersey number 2 when playing.

Post-timeskip, he has let his hair grow out a little.


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 numerous altercations since they first met but shared in their goal of wanting to dominate nationals[2].


Karasuno High Team Formation Arc

Shortly before the match’s commencement, Kai supports Kuroo’s analogy of the team being “blood” and Kenma being the “brain” when the setter complains about how he finds it embarrassing. As a reference to one of Daichi’s impressive saves in the game, some spectators notice how despite the two third-years not standing out, they are still extremely important members of their team after Kai manages to narrowly dig a ball. Shortly after, Kai nearly tricks Hinata into thinking that he is going to be the rally’s hitter, but the rookie is not fooled.

Following the matches concluding, Daichi notices Asahi intimidating Shibayama. Although he does not directly tell the ace, Daichi gets mad at him for taking an intimidating approach despite his intentions being good. Kai notices this and defends Asahi saying that from his perspective, it looks like a conversation between father and son rather than Daichi’s thinking of looking like attempted kidnapping.

Tokyo Expedition Arc

Kai mostly appears during the practice matches.

Tokyo Prefectural Qualifiers

Nekoma vs. Fukurōdani

Kai participates in the match between Nekoma and Fukurōdani. Before the game starts, Kai is not surprised when Suguru and Kuroo get into an argument. Despite Yamamoto’s embarrassment, Kai is thankful for Akane’s support in cheering. During the match’s beginning portion, Kai is able to save a missed block from Kuroo.

During break, Kenma tells his observations of Bokuto’s habits that day. When Kai suggests switching their blocking arrangement to stop his line shot, Kenma agrees but first suggests that they attempt to weaken Bokuto's play. Sometime later, after another timeout from Nekoma, Kai tells the team to be wary of Bokuto’s serve as he is rotated. After serving, Kai is able to dig it nicely, which frustrates Bokuto since he had been feeling good when serving that.

After Nekoma’s loss, Kai remarks that it’s been a while since Fukurōdani has won in straight sets.

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. Sometime after the second set begins, Kai notices Lev's distress and assures him that the team would always be behind the rookie blocker to support him if he were to fail. Near the end of the match, Takachiho makes it obvious that he is attempting to aim at a perfect place to target Yamamoto. Kai notices this and easily receives Takachiho's serve, which frustrates Nohebi's player.

Eventually, Nekoma was able to win the match and Kai is seen happily celebrating Nekoma's victory with Kuroo and Yaku.

Tokyo Nationals Arc

Nekoma vs. Kiyokawa

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

Nekoma vs. Sarukawa

The night before, Kai tells Yaku to have more faith in their juniors as he is skeptical about them getting to nationals the next year. When hearing Kuroo explain Kenma growing to enjoy volleyball, Kai concludes that Kenma would have quit if he didn't like it. As Yaku remarks that Kenma's gotten more determined after meeting Karasuno, specifically Hinata, Kai confirms this. After their conversation about Kenma ends, Yaku and Kuroo get into a short argument and Kai apologizes to the people around them.

During the match, Kai notices Sarukawa doing a feint and he gets praised by the announcers. Near the end of the second set, Kai is set to as Kenma notices that Sarukawa has caught on to his strategy. After Kenma tells the team to send the ball to him, they all proudly assure him that they would do so. After their victory, Kuroo and Kai tease Kenma to him admitting that he cares about the team.

Nekoma vs. Karasuno

For majority of the first and second set, Kai is mostly seen taking part in receives and blocking; most notably he is seen tasked with trying to receive as many of Kageyama's serves as possible. At the end of the second set, Kai is subbed out for Inuoka, so that the first-year could assist Lev in trying to block Hinata. Kai would return to the game at the start of the third set and would right away be the one to receive Kageyama's second serve.

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

Karasuno vs Kamomedai

During Karasuno’s match against Kamomedai, Hoshiumi impressively receives Tsukishima’s spike after having been set to perfectly and Kai is impressed but worried at how good his receiving skills are.

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 and digging.

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 year at Nekoma High and is shown to have been amused by their antics since before they officially joined the volleyball team. When playing together, they are shown to have great faith in one another and a strong sense of teamwork.


  • "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)


  • 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[3]. He did not rank in the second poll[4].
  • Kai is the oldest of the Nekoma third-years and the sixth oldest third-year in the series.
  • Nomenclature:
    • Nobuyuki (信行)
      • 信 - Trust
      • 行 - Go
    • Kai (海) - Sea