"Warm-Ups" (Japanese: ウォームアップ Wōmuappu) is the thirty-eighth chapter of the Haikyū!! series written and illustrated by Haruichi Furudate. It was published in the 51st issue of Weekly Shōnen Jump’s 2012 series.
Aone sets his sight on Asahi. Hinata tries to overcome his excitement and nervousness by remembering his scariest experience ever. Daichi rekindles with Ikejiri, his former junior high teammate. Ikejiri remembers what kind of player Daichi was and notes that the latter had become stronger. Aoba Johsai arrives and catches everyone’s attention.
Karasuno faces Date Tech in the hallway. Aone suddenly raises his finger and silently points to Asahi. Nishinoya tries to step in but to his surprise, Asahi holds him back and glares back at the Date Tech member. The rest of Karasuno are shocked by Asahi's lack of fear. Before either side can say anything, Date Tech's captain Moniwa cuts in and apologizes frantically for Aone's behavior. Futakuchi then helps his captain push Aone away, but smugly warns the Karasuno members to be ready for their match this time.
As they leave, Sugawara compliments Asahi's courage, only to see the ace sweating fearfully. Nishinoya teases him for being weak off the court as the team walks away. At their changing area in the stadium, the members take off their jackets and Kageyama notices Hinata shivering. Hinata exclaims that he's shaving with excrement, his anxiety causing him to mispronounce "shaking with excitement". Kageyama worries about this, remembering his experience at the practice match against Aoba Johsai. Sugawara points out that Asahi isn't nervous, even though he's just as timid. The latter replies that Hinata just needs something to distract him from his anxiety and tells the first year to think of the scariest thing he had ever experienced. Hinata thinks of all sorts of things for a minute before suddenly remembering Kageyama's expression when he'd served a ball straight into the back of the setter's head during the Aoba Johsai practice match. This calms Hinata down immediately.
The team soon heads out to warm up for its first match. Hinata and Kageyama are excited for their first official game with Karasuno. On the way, Daichi's approached by Ikejiri and the former tells his team to go on ahead. The two catches up and Ikejiri notes that his junior high friend seems different. Ikejiri tells Daichi about their earlier almost-encounter and notes that Karasuno seems to be strong. He remarks that his own team is called a weakling school before stopping himself, remembering something from junior high.
Their team had won their opening match for the first time ever in their final game of junior high, but they then lost to a champion school in the second match. When they felt like giving up, Daichi remained determined and even chased the ball to the last second. Everyone felt relieved since they knew a loss was inevitable, but only Daichi was miserable. However, for some reason, Ikejiri felt jealous of his friend.
Back in the present, Ikejiri announces that it doesn't matter whether a school is weak or strong. On the court, what truly matters is defeating the opponents. Daichi accepts his challenge with a confident grin.
Elsewhere, Aoba Johsai enters the court. Irihata wonders where Oikawa went and Yahaba replies that the third year was stopped by some girls outside. The coaches send Iwaizumi to take care of the problem. As Oikawa's agreeing to a picture, Iwaizumi spikes a ball into the back of his head. When Oikawa turns to complain, the wing spiker simply glares menacingly back at him. Intimidated, Oikawa goes back to his team.
As the Karasuno members are warming up, Hinata spots Aoba Johsai in the bleachers and point out Kindaichi as "shallot-head". The latter's confused by the nickname as Kunimi laughs and teases him about it. Oikawa then greets Kageyama and Hinata cheerfully and the two scowls back as they think of their possible match against Aoba Johsai.
- Kōshi Sugawara
- Asahi Azumane
- Tobio Kageyama
- Yū Nishinoya
- Shōyō Hinata
- Daichi Sawamura
- Yutaka Obara
- Takanobu Aone
- Kenji Futakuchi
- Ryūnosuke Tanaka
- Kei Tsukishima
- Tadashi Yamaguchi
- Hayato Ikejiri
- Kiyoko Shimizu
- Yūtarō Kindaichi
- Nobuteru Irihata
- Sadayuki Mizoguchi
- Issei Matsukawa
- Hajime Iwaizumi
- Takahiro Hanamaki
- Shigeru Yahaba
- Tōru Oikawa
- Akira Kunimi
- Aone has a habit of "locking on" (pointing at) aces of other teams.
- To mollify himself before a match, Asahi thinks of the scariest experience he'd ever had.
- Hinata’s scariest memory was Kageyama’s expression after the middle blocker had hit a volleyball into the back of his head during the Aoba Johsai practice match.
- Iwaizumi is Oikawa’s chief disciplinarian.
- Oikawa is popular among girls, even those from other schools. At tournaments, they would gift him with candies or letters and ask him to take pictures together.
- Hinata’s nickname for Kindaichi is “Shallot-head.”
- Tokonami is known as a weakling school.