The other schools who will compete with Kyosumi in the nationals are selected. Among them are Miyamori, Eisui All-Girls, Himematsu, and Rinkai All-Girls, along Shiraitodai and Achiga. As all the representatives arrive for the National tournament, the first day is dedicated for all the teams to settle themselves at Tokyo, as Saki and her friends spend some downtime with members of both Kazekoshi and Ryuumonbuchi. Despite not taking part in the tournament, the girls from Tsuruga also arrive to watch it as well. At the tournament lottery draw, a lost Saki has a short encounter with the Achiga girls before reuniting with her team mates. Kiyosumi draws a bracket in line with both Himematsu and Eisui. Per the schedule, Kiyosumi does not play until day 3 and Hisa declares that they will spend the second day leisurely in preparation for their first match.

As the day of Kiyosumi's first round arrives, Saki states her determination to reach the finals before she can talk to Teru. After receiving some encouragement from Ryuumonbuchi and Tsuruga, Hisa receives a video from her school showing the support of all their friends and classmates. Moved by how many people have surrounded her in the past two years, Hisa thinks back to the training camp she held with Ryuumonbuchi, Kazekoshi, and Tsuruga. During the camp, Touka unconsciously enters a 'cold state' where she manages to beat Saki, Koromo, and Fujita. Later, Hisa invites Nodoka and Yuuki's friends from middle school, Maho Yumeno and Hiroko Muruhashi, to play with Saki and Nodoka, where Maho shows a fearsome ability.

Nodoka recalls how she met Yuuki in Takatoobara Middle School and joined its mahjong club, where she also met Maho. Back at the training camp, Maho uses her ability to mimic other people's playstyles and shocks Saki when she copies her rinshan kaihou. Maho ultimately loses the rest of her hands though, as she can only mimic a certain ability once per match and her base skills are poor. It is shown that Hisa had invited Maho to the camp to both improve Mako's repertoire and give Saki a much-needed sense of fear, whilst she herself trains with Koromo, Yumi, and Mihoko. Returning to the present, Kiyosumi makes it through the first round after Hisa's victory, along with Himematsu. A few days later, Kiyosumi faces their second-round match with Yuuki going up against Eisui's Komaki Jindai, Miyamori's Shiromi Hosegawa, and Himematsu's Suzu Ueshige.

Yuki makes a strong play during the game's east round, particularly against Suzu. On the second hand, however, Shiromi makes a strong play whilst the 'awakened' Komaki prepares to make her move.

Just as the first player's match is about to end, Komaki makes a strong play against Yuki, knocking Kiyosumi out of the lead. The second match soon begins with Mako up against Miyamori's Aislinn Wishart, Eisui's Tomoe Karijuku, and Himematsu's Yuuko Mase. Although Miyamori has high hopes for Aislinn's ability to visualize everyone's tiles, Mako manages to counter her plays with low-scoring hands, completely disrupting her flow, bringing Kiyosumi back their lead.

During the lunch break, as teammates, commentators, and spectators have lunch with their respective groups, Hisa heads to the game room ahead of time, where she feels a chilling aura coming from the other players; Eisui's Haru Takimi, Miyamori's Kurumi Kakura, and Himematsu's Hiroe Atago. As the round goes on, Hisa struggles to concentrate, falling into Hiroe's plays several times and losing a lot of points. She soon remembers the most important thing about mahjong is to have fun, and she manages to regain some points with her signature bad wait. Despite falling to the last place at the end of the first half, Hisa feels freed from her nervousness and is prepared to give the second half her all.

Despite plays by both Hiroe and Kurumi, Hisa keeps the spirit of fun in her heart and get her own play at the end, ending the round with Kiyosumi in second place. Nodoka soon hears into the vice-captain's match against Himematsu's Kinue Atago, Miyamori's Sae Usuzawa, and Eisui's Hatsumi Usuzumi. As the match begins, Nodoka immediately brings out her 'Nodocchi' play style whilst Hatsumi brings out her "Gates of Evil".

Aware of Hatsumi's playstyle, Sae uses her ability to seal off her hands, though they are both surprised by Kinue's play. The rest of the half sees the three battling it out, with Nodoka seemingly oblivious to everything. After the first half, Sae, who is under stress from her power, recalls when Toshi became Himematsu's teacher and advisor. As the second half gets underway, Nodoka starts making her comeback.

Hatsumi continues to lose points whilst Kinue helps put Himematsu into the lead, though Hatsumi manages to make a huge play before the match's end. It is soon time for the captain's match between Saki, Eisui's Kasumi Iwato, Himematsu's Kyouko Suehara, and Miyamori's Toyone Anetai. The round starts off with Kyouko scoring several consecutive wins, but Saki soon fights back with her rinshan kaihou, before Toyone starts making consecutive 'chasing riichi' plays against Kyouko.

As the second half begins, Toyone brings out another one of her plays, the naked wait, and moves into second place. Toyone recalls her first game with the other Miyamori players, who welcomed her in with open arms. Toyone soon performs another naked wait and moves into first place, pushing Kiyosumi into third.

Kasumi brings out her dormant ability to draw a specific type of tiles to move into the lead, whilst Kyouko starts fighting back by drawing on her experience in three-player mahjong. Saki manages to score another rinshan kaihou and soon moves into the lead again with consecutive wins, displaying tactics that strike fear into the other players.

Whilst pondering Saki's actions, Kyouko manages to move into second place, slightly ahead of Eisui. As everyone is put under pressure to win the final hand, it is Saki who ends the match with a cheap hand, bringing Kiyosumi and Himematsu into the semi-finals. Looking over Saki's records, Kyouko comes to understand that, if they were playing regular matches, Saki would have had a +-0 score. Whilst Himematsu enlists the help of pro Yoshiko Kainou to help with a training camp for the semi-finals, Eisui invites Miyamori to join them on a trip to the beach. Meanwhile, Saki laments not being able to break out of her old playing style, worrying she may not be able to win against Kyouko a second time. Elsewhere, Nodoka has a dream about her old friend.

As everyone besides Saki get together to watch the Side A semi-finals match, in which her old upperclassman from middle school is participating, Nodoka is surprised to find Achiga, whose mahjong club she used to be a part of, is participating in the match as well. She and Yuki head to the auditorium to watch their match, but Saki finds herself unable to join them, as knowing her sister is there trigger some traumatic flashbacks for her. Unable to get into the main hall, Nodoka and Yuki are given the opportunity to watch the match in the press room. She soon comes across Achiga's team, with Nodoka and her old friend Shizuno stating their determination to meet each other in the finals. As Saki returns to her inn, where she is visited by Koromo and Hajime, Nodoka is interviewed by the press about how she came to know the Achiga girls. Afterward, Nodoka and Yuki deliver some tacos to Kirame, who uses them to comfort the other Shindouji players following their loss in the semi-finals.