Hinata is inspired by the Small Giant playing volleyball on TV. Three years later, Hinata goes to his first-ever volleyball tournament and his team is set to play against Kitagawa Daiichi, the school of Kageyama Tobio, also known as the King of the Court. Their match against each other leaves them both interested in their skills and sparks a rivalry. However, they meet again next year, but this time as teammates in their new high school: Karasuno High.

Hinata arrives at Karasuno High School determined to join the volleyball club and defeat Kageyama. He is shocked when he walks into the gym and finds that Kageyama is a potential member of the Karasuno team as well. They fight right away and when captain Daichi Sawamura arrives, he throws the two out and tells them they can't join the club until they start to get along. Instead of agreeing to work as a team though, they challenge the upperclassmen to a match on the condition that if they win, they join the team.

Sugawara starts helping Hinata and Kageyama practice in the morning. After hearing Hinata's jaded opinions of Kageyama, Sugawara encourages him to work with the first-year setter because he could become Hinata's most formidable ally. As the days pass, Hinata slowly improves, but his relationship with Kageyama isn't going anywhere until they encounter Tsukishima and Yamaguchi, the other first years applying for the club. Tsukishima's insults about Hinata's height and Kageyama's past motivate the two to team up to win on Saturday.

The practice match that will determine Kageyama and Hinata's future with the Karasuno High Volleyball Club begins as Kageyama, Hinata, and Tanaka battle Tsukishima, Yamaguchi, and captain Daichi in a 3-on-3 match. Kageyama and Hinata can't coordinate initially due to Kageyama's old setting habits and constant harassment from Tsukishima but with encouragement from Sugawara, they manage to figure out a way to utilize their skills to create the perfect attack.

Kageyama and Hinata's combos start improving, and Hinata's skills as a decoy begin to emerge. Kageyama, Hinata, and Tanaka are able to rally and win the 3-on-3 first year match, allowing Kageyama and Hinata to be accepted as official team members. As soon as they receive their team jackets, advisor Ittetsu Takeda arrives and announces a practice match with Aoba Johsai. However, there is one condition: Tobio Kageyama must act as the setter for the entire match.

Karasuno arrives at Aoba Johsai, but Hinata's anxiety doesn't change. Before the match even begins, Kageyama runs into his old teammate, Kindaichi, who continually calls him king of the court and brings up his past. Karasuno does poorly at first due to Hinata's mistakes but once the match gets underway, Hinata and Kageyama's quick attack proves to be an effective weapon. As Karasuno appears to be winning, Kageyama reveals that he doesn't think Aoba Johsai's current setter is the official one.

Oikawa suddenly shows up for the practice match. He is revealed to be Aoba Johsai's captain and official setter. He is also Kageyama's senpai from middle school. Oikawa enters the game and immediately targets his perfect serves at Tsukishima who can't receive them properly; this allows Aoba Johsai to catch up to Karasuno. It isn't until Daichi changes their formation that Karasuno is finally able to win the match against Aoba Johsai. However, Oikawa says that when they next meet, Aoba Johsai will be using all of its aces from the start, and a very different result will be expected. As they leave, Daichi reveals that Karasuno also has a few surprises. Their libero, Yū Nishinoya, is about to return and completely change Karasuno's dynamics as a team.

While practicing, Kageyama's shocked when a stranger runs into the gym and perfectly receives his serve. The stranger's revealed to be Nishinoya, Karasuno's libero who had been away due to club activities suspension. After introductions, Nishinoya learns that Karasuno's ace, Asahi, isn't back and angrily storms out. Seeing how unhappy the upperclassmen are without the ace, Hinata and Kageyama go to him to try to convince him to return. Meanwhile, Takeda continues to pursue Keishin Ukai as the next coach of Karasuno High. Ukai persistently refuses to help, but Takeda comes up with a plan that he believes will pull Ukai into the world of coaching.

Keishin Ukai agrees to Karasuno's coach after he learns of the upcoming practice match, but only until the practice match is finished. To familiarize himself with the current players' abilities, he arranges a match for them against the neighborhood volleyball association. Nishinoya and Sugawara are placed on the association team to allow an even match, as only four of the players had been able to make it. Filling in the last spot is Asahi Azumane. Now, Asahi must prove he deserves the title ace and get past the triple block of Kageyama, Tanaka, and Tsukishima to regain his confidence.

As Asahi regains his confidence as the ace, Hinata and Kageyama finally get to use their quick. Ukai's shocked at the two's coordination and Kageyama's skills, which he compares with Sugawara's dependability and experience, further complicating his decision on which player to pick as the official setter. On the side, Hinata gets distracted as he compares himself with Asahi and how he would never attain that level of strength. However, after a mishap and encouragement from Kageyama, Hinata finally understands his importance to the team as a decoy.

The training camp officially begins and the players ready themselves for the showdown against Nekoma. Surprising backstories of the upperclassmen are revealed and Ukai struggles with his decision on the official setter; in the end, he decides on Kageyama. Nekoma arrives in Miyagi and overwhelms in its practice matches while Hinata unknowingly meets its setter, who looks forward to playing against the first year. The match against Nekoma soon proves to be Karasuno's toughest one yet.

Nekoma and Karasuno begin their match with Kageyama and Hinata connecting on a quick attack that gives Karasuno the 1-0 lead. Nekoma realizes that they're up against a genius setter, so they decide to start marking Hinata. Hinata's blocker gets used to his speed, and starts to block his shots, allowing Nekoma to win the first set 25-22. However, Hinata isn't discouraged and continues trying. Suddenly, he figures out a way to change his spike path mid-air and realizes that he now has a new weapon to go along with his quick attack.

Nekoma and Karasuno play the second set to an epic 25-23 showdown but in the end, Karasuno falls just short. However, the two schools reform a rivalry that is better than time could imagine. The two come to realize they both have similar personalities on their teams, and they both have players with goals and ambitions. Best of all, they realize they are starting to unite as a team. Despite being thoroughly crushed, Karasuno vows to get revenge on the national stage. In the end, Ukai agrees to become the Karasuno's full-time coach.

The bracket for the Interhigh is announced. Karasuno has its final practices and works on back-end spikes and signals. Yamaguchi secretly seeks out Shimada's help with the jump float serve so he won't be the only first year without an ability to contribute to the team. As the Interhigh approaches, Hinata remembers that around this time last year, Yukigaoka'd lost to Kitagawa Daiichi. Determined, Hinata vows to win at the Interhigh, and eventually beat Kageyama.

The first day of Interhigh finally comes. Karasuno walks into the stadium to rumors about it being "Flightless Crows", but the players are determined to change their reputation. Daichi catches up with a former teammate before they vow to defeat each other. The match between Karasuno and Tokonami begins and Karasuno easily takes the first three points. Kageyama and Hinata unveil their quick strike and Asahi proves his strength as the ace. The match has just begun, but everyone has realized that Karasuno is back and better than ever.

Karasuno dominates Tokonami and easily wins the first set, but the players don't falter and continue giving their full efforts. Tokonami begins to lose hope and Ikejiri thinks back to a match from junior high where Daichi gave a speech to the team. He repeats a quote from his friend, motivating his current teammates to give their full efforts as well. Despite that, Karasuno ends up winning easily. Ikejiri is saddened by this, especially since he's a third year now, but is happy for his friend and tells Daichi to continue winning for Tokonami. Karasuno now heads towards its match against Date Tech, the team that had caused Asahi to quit volleyball.

Date Tech and Karasuno battle it out in the second round, with neither side leading for long. While Date Tech easily blocks Karasuno's attackers, Karasuno defense holds strong thanks to Daichi and Nishinoya. Kageyama begins to enact the plan Ukai came up with: force Hinata to stand out to take the attention off the other attackers. The two first years use their usual quick strike and throw Date Tech off. When Aone starts keeping up with it, Kageyama switches his focus to Asahi, giving the ace a toss that enables him to push past Date Tech's defense and finally, get revenge for their previous match. Karasuno has used up its secret weapons now. From this point on, they can only fight to win the match.

Karasuno manages to gain momentum in set 1 and steals the game 25-21. For set two they perform a double rotation to get Hinata away from the Giant #7. While this frees up Hinata for more quick attacks, it also means the matches result will rely heavily on Asahi's ability to blast through the Iron Wall as he faces #7. When Hinata becomes the vanguard up front, Karasuno is able to slowly increase their lead. However, Hinata rotates to the back with the score 24-22. Should they go to a third game, Karasuno knows they will be at a disadvantage. It all relies on Asahi's skills to get past the wall. As the match ends and Karasuno is leaving the gym, they look over to see Aoba Johsai is up 24-13 in their 1st round match first set.

Karasuno observes Aoba Johsai's match and is unnerved by Oikawa's skill in serves and tosses, especially Kageyama, who has been in Oikawa's shadow since junior high. The match against the two teams takes place the next day, and Karasuno seems to be more motivated than ever. Right away, Aoba Johsai gets the upper-hand with Oikawa's setter dump and skillfully executed techniques. However, Kageyama reveals tricks of his own and performs a server dump right back, cutting Aoba Johsai's lead to 2-1.

Aoba Johsai starts to overwhelm Karasuno and builds a huge point gap. Things get even worse when Oikawa figures out the secret signals Kageyama and Hinata use for their quick strike, and Kageyama begins to panic. This ruins his momentum as he goes too fast with his tosses while Oikawa continues taking point after point. With no timeouts left for this set, Ukai has no choice but to sub Sugawara in.

Sugawara subs in for Kageyama, and Aoba Johsai wins the first set. Kageyama is shocked as he watches Sugawara reveal his real setting abilities. Karasuno takes the lead in the second set thanks to Sugawara's tactics, but Oikawa's serves are still a major problem. After observing Sugawara's interactions with his teammates, Kageyama finally learns what it means to be a setter–and a team member.

After being subbed back in, Kageyama attempts to communicate with each of his teammates and learns how to accommodate the different attackers. He and Tsukishima manage to sync with each other and become an unstoppable force. Oikawa watches this revel and remembers his bitterness and jealousy towards Kageyama from junior high and his goals to defeat Ushijima. He's not backing down and wants to defeat Karasuno more than ever.

Aoba Johsai begins to pull away in the third set, forcing Coach Ukai to make some drastic decisions. Yamaguchi is subbed in as a pinch server, but the pressure proves to be too much to overcome. A service error occurs, but the error allows Karasuno to calm down and motivates it to fight to its full efforts. Karasuno is finally right at Aoba Johsai's back.

Kageyama matches Oikawa point for point as the teams become dead even. The long sets take a toll on both teams' energy and Kageyama starts to notice a change in a former teammate's attitude towards volleyball. It soon becomes clear to him the difference in his and Oikawa's abilities but just as he begins to despair, Hinata reminds him that he belongs on Karasuno now. Oikawa acknowledges that Kageyama has realized what teamwork means and is no longer the Solitary King. However, Aoba Johsai blocks Hinata's quick in the end and wins the match.

After suffering a heartbreaking loss to Aoba Johsai, the third years must decide if they will retire or participate in the spring tournament. Kageyama and Hinata vent their frustration in the gym and determine to keep moving forward. The winner of the fall tournament is revealed, and Karasuno begins its first real practice to get ready for the spring tournament.