Sei and Reiji's victory in the tournament causes Chairman Mashita to panic, with his Arista resonating all Plavsky particles in the PPSE Stadium to form a 1/144 scale replica of the Zeon space fortress A Baoa Qu over the facility. The Gunpla Fighters must band together to break into the fortress and destroy the Arista before it produces disastrous results.

In the final round of the tournament, Meijin Kawaguchi the 3rd unveils the true form of his Gundam Amazing Exia. However, he brings forth a disturbing aura in the arena reminiscent of his predecessor.

Yuuki must prove himself worthy of the name "Meijin Kawaguchi the 3rd" when he battles Julian Ayers Mackenzie, a British Gunpla Fighter who was to have taken that title three years prior.

On the first day of the tournament finals, Mao is scheduled to battle Sei and Reiji. But when he cannot think of a strategy to defeat the Star Build Strike Gundam, he returns to his mentor, Master Chinan, and asks him to teach him the master's ultimate technique.

Sei and Reiji must go through Nils in order to continue their quest for the championship. Desperate to prevent the duo from advancing, Baker offers to have PPSE sponsor Nils, but knowing very well not to trust her, he arranges for a secret meeting with Sei and Reiji to extract the secrets of Plavsky particles from them.

For day three of the tournament, containers with random weapons are placed in the battlefield for the Gunpla Fighters to use in their battle; each contestant is assigned a container number to use. Sei and Reiji are assigned to battle Luang Dallara, who already gave them trouble at the battle royal. Worsening the situation is Reiji's wrist injury from a street fight outside the arena grounds.

With their loss in the Gunpla race dropping them to 17th place, Sei and Reiji must leave no room for error in the eighth period of the tournament in order to make it to the finals. However, they have to go through Fellini in the process.

Yuuki makes his World Championship debut as PPSE's Meijin Kawaguchi. Meanwhile, on the second day of the tournament, all of the participants must face each other in a battle royal until only one-third of the lineup remains.

Fellini faces Aila in the quarterfinals, much to Sei and Reiji's shock as they finally discover her real identity. Aila is pressured to win the championship due to the arrival of the Team Nemesis Chairman, who has promised the trophy to his grandson for his birthday.

After shocking the Gunpla world by defeating Luang on the first round, the Renato Brothers and their GM Sniper K9 set their sights on Meijin Kawaguchi.

Following Aila's revelation as a Gunpla Fighter, an angry Reiji vows to defeat her in the tournament.

Sei Iori is a talented Gunpla builder, but lacks the confidence to become an effective fighter in a Gunpla Battle. One day, he meets Reiji, a mysterious red-haired boy, who displays his exceptional skills as a Gunpla Fighter by defeating Susumu Sazaki with Sei's newly constructed Build Strike Gundam.

As a reward for winning the Gunpla Battle Japan 3rd Block Championship, Sei and Reiji, along with China, Rinko, and Mr. Ral, take a vacation at a beachfront inn. But their vacation is cut short by a former Gunpla Builder who threatens the innkeeper to give him their property.

The final round of the Gunpla Battle Japanese Championship tournament has finally begun. Taking the initiative, the Try Fighters opt to fight inside a space colony. Sekai and Fumina split off from Yuuma, and both groups make preparations to intercept the Gunpla Academy. The audience members watch this quiet start with bated breath, until the silence is broken by Kijima’s Transient Gundam. Having anticipated the Try Fighters’ plan, Kijima launches a diversionary attack to distract them, and at the same time Yuuma finds himself in combat against Shia and Adou. As the teams continue trading blows in a fierce back-and-forth struggle, Yuuma and Fumina battle Shia and Adou of the Gunpla Academy to mutual destruction. Only Sekai and Kijima remain, fighting desperately to the brink of collapse, until they ultimately reach the time limit and usher in the first overtime battle of the tournament.

Nils Nielsen, a 13-year-old genius, joins the American Qualifying Round of the World Championship to learn more about the secrets of Plavsky particles. Meanwhile, in Finland, Team Nemesis receives a new fighter named Aila Jyrkiainen from the Flana Institute.

Now that their end-of-term exams are over, the Try Fighters are going to a training camp to prepare for the national tournament which will take place during summer vacation. Mr. Ral has kindly arranged for them to visit the Nielsen Labs, a facility equipped with the industry's leading battle environment, where all the regular national tournament teams gather. There, Sekai and his comrades end up agreeing to a practice match against team White Wolf from the Gabai Institute, the representatives from Kagoshima, who were using the battle system for a mock battle. Thanks to Sekai, however, the Try Fighters arrive later than planned and find that in the meantime the White Wolf members have been wiped out by a single Gunpla. When Yuuma sees this Gunpla, he abruptly intervenes and challenges it to battle. Fumina and the others are bewildered by Yuuma's unexpected action, but it was this same Gunpla that drove Yuuma away from Gunpla Battle two years earlier.

The Try Fighters have won the West Tokyo qualifying tournament for the Gunpla Battle Japanese Championship. As Sekai recovers from the damage of assimilation, he thinks ahead to the powerful new opponents gathering at the national tournament. Meanwhile Sekai's sister Mirai Kamiki, who works as a fashion model, has been signed up for the "Tokyo Gunpla Collection," an event meant to fuse Gunpla with fashion. The highlight of the event will be a Gunpla Rally between modeling agencies. With the help of Sekai and Yuuma, Mirai successfully builds her Mama-Beargguy. On the day of the Gunpla Collection, Sekai and the others go to visit Mirai after the glorious fashion show. Here they encounter TAKU, the leader of the popular rock group SGOCK Third Generation. Somehow or other, thanks to Sekai, Mirai may now have to go on a date with TAKU depending on the outcome of the race.

During a Battle Royal among representatives from each school under the Meijin's supervision, Sekai Kamiki and Wilfrid Kijima have acknowledged each other as rivals, and they promise to fight again at the national tournament. Yuuma Kousaka, meanwhile, declares that he will get revenge on Saga Adou and looks to the tournament with fresh resolve. Elsewhere, the final regional qualifiers are completed, after being delayed by problems with the venue. The winner of the Osaka qualifiers is team Build Busters from Tendaiji Academy, to which Minato Sakai now belongs. With the national tournament 10 days away, the champions from the participating schools steadily make their preparations. Fumina and her comrades, aiming to defeat the Gunpla Academy, set out to power up their own Gunpla and address their shortcomings based on their experiences at the Nielsen Labs. As the start of the tournament draws near, Gyanko and others come to help, and at last the Try Fighters' new machines are completed.

Once upon a time, the Gunpla Battle world championship was held at the PPSE Stadium. After the Plavsky particle accident seven years ago, the damaged stadium was demolished, and a monument was placed there bearing the names of previous champions. Now, the Gunpla Battle Japanese Championship tournament is about to begin at the Yajima Stadium, which has been newly constructed next to this site. As champions gather from every prefecture, having fought their way through the regional qualifiers, Sekai again encounters Wilfrid Kijima of the Gunpla Academy. Meanwhile, Yuuma learns that Minato Sakai is also entering the tournament as one of the representatives from Osaka. The next day, brackets are drawn after the opening ceremonies, and the Try Fighters immediately enter battle as they are assigned the first match of the tournament. Their opponent is Okhotsk Academy, representing South Hokkaido, a team that placed in the best 8 of last year’s national tournament!

Minato Sakai and his teammates from Tendaiji Academy, representing Osaka, easily make it through the first round of the tournament thanks to the overwhelming power of their unique Gunpla, the Tryon 3. Other rivals that Sekai and his comrades met at the Nielsen Labs, such as the Gabai Institute from Kagoshima and the Toritsu Academy from Niigata, likewise survive the first round. As the tournament enters its second round, the top-seeded Gunpla Academy finally enters battle. The Gunpla Academy’s third fighter is Shia Kijima, the girl who taught Sekai how to repair the Build Burning. The attention of the whole venue is focused on the Gunpla Academy as it battles Honmoku Academy, representing Kanagawa. But its team leader, Wilfrid Kijima, orders Shia to sortie alone as a penalty for waiting until the very last minute to complete her Gunpla. Now Shia’s G-Portent must confront Honmoku Academy on its own.

After defeating the veterans of Seiren Technical College, the Try Fighters win an easy victory in the third round, as their opponents self-destruct! They are advancing to the quarterfinals! Fumina and the others observe the following match to see their next opponent, Joto Middle School. After the match, two members of the Joto Middle School team beg the Try Fighters to let them win for the sake of their team leader Shimon Izuna’s little brother Mamoru, who is battling a serious illness. Fumina and the others are bewildered by this unexpected request, and begin to question their own reasons for fighting. In order to see the situation for himself and test his resolve, Sekai goes alone to the hospital where Shimon’s brother is being treated. Here, Sekai issues a straightforward declaration of war to Mamoru the Gunpla builder, and to his opponent Shimon!

The Try Fighters have been utterly defeated by Gundam The End, the Gunpla controlled by Saga Adou of the Gunpla Academy. Yuuma is unable to hide his shock at witnessing the vast difference in their abilities, and he flees the scene, leaving his teammates behind. The concerned Fumina asks Mr. Ral to look after Sekai, who has collapsed as a result of assimilation, while she goes in search of Yuuma. Meanwhile, Meijin Kawaguchi appears before the dispirited Yuuma. Without explanation, the Meijin spirits him away in his motorcycle sidecar. Fumina sees them go, and is then approached by Lady Kawaguchi, who warns her that "As a Gunpla builder and fighter, you're definitely lacking something." To restore their lost confidence, and show them what they lack, the two Kawaguchis challenge Yuuma and Fumina to battle!

Having recovered from his battle with Adou, Sekai heads for the Labs' workshop to repair the Build Burning Gundam, and encounters a mysterious girl. Thanks to the girl's advice, Sekai finishes repairing the Build Burning, and the next day he goes to the Labs' battle room with Mr. Ral for special training. There he meets Kei Karima from Honmoku Academy, representing Kanagawa, who suggests they play a practice match. His goal is to learn the strength of the Gunpla Academy, and when Sekai realizes this, he cannot hide his anger. At this point Wilfrid Kijima, the ace of the Gunpla Academy, intervenes, as does the Gabai Institute team that represents Kagoshima. It seems the situation will get out of hand, until Meijin Kawaguchi suddenly appears on top of the battle system. Thus begins a Battle Royal among representatives of each school, under the Meijin's supervision.

The Try Fighters have made it into the semifinals as one of the best four teams. A drawing is held to determine the brackets, and they are matched up with Suiryu Academy. Meanwhile, Gyanko’s team from St. Odessa Girls’ School will face last year’s regional champion, the Miyazato Institute. As if from the pressure of fighting the previous champion school, Gyanko comes crying to Sekai before the battle. Out of compassion, Fumina leaves Gyanko alone with Sekai at a fast food restaurant, but it turns out that Gyanko is just playing on Sekai’s sympathy to make him agree to a date. Despite her meek behavior, Gyanko’s strategy fails when Sekai realizes her intentions. Then they suddenly run into Yomi Sakashita and Akira Suga from the Miyazato Institute, and Suga declares that Sekai’s Jigen Haoh school of kenpo won’t work on him. As they go to face their respective semifinals opponents, Gyanko and Sekai promise each other that they’ll meet in the final round…

The Try Fighters' opponent in the final round will be last year's regional champion, team G-Master from the Miyazato Institute. The two teams prepare for the final battle, each with their own resolve and desires. The battlefield for the final match is the space fortress Solomon. Outside the fortress, Yuuma's Lightning Gundam exchanges fire with Sudou, who is using the Mega-Shiki built by Minato Sakai of the Shingyo school. Meanwhile, Sekai and Fumina begin a battle inside the fortress with Suga and Sakashita, who were already lying in wait for them. As the fierce fighting continues, Sekai and Fumina exit the fortress. Sudou attempts to shoot them down with his high mega particle cannon, but Yuuma stops him as they trade simultaneous blows. Battered and broken, Sekai and Suga cling to the hope of victory, clashing in a final desperate effort.

Having transferred to the Seiho Academy, Sekai discovers that he and Yuuma are in the same class. He challenges Yuuma to a battle but is bluntly rejected. Meanwhile, the school's student council has decided to merge the Gunpla Battle Club with the Plastic Model Club. To survive on its own, the Battle Club must defeat the Plamo Club in battle, and Yuuma is among the latter's players. With the Battle Club facing three-to-two odds, the battle seems like a mere formality, but Fumina's tactics let them put up a good fight. Miyaga loses his temper and deploys the huge mobile armor Agrissa, finally backing Fumina into a corner. But Yuuma, unable to accept that his club president is trying to win by ignoring the previously agreed rules, teams up with Sekai to destroy Miyaga's Agrissa. Thus, with the addition of Yuuma, team Try Fighters is finally formed!

Sei and China meet Mao Yasaka, a young Gunpla Fighter from Kansai Prefecture.

Having transferred to the Seiho Academy, Sekai discovers that he and Yuuma are in the same class. He challenges Yuuma to a battle but is bluntly rejected. Meanwhile, the school's student council has decided to merge the Gunpla Battle Club with the Plastic Model Club. To survive on its own, the Battle Club must defeat the Plamo Club in battle, and Yuuma is among the latter's players. With the Battle Club facing three-to-two odds, the battle seems like a mere formality, but Fumina's tactics let them put up a good fight. Miyaga loses his temper and deploys the huge mobile armor Agrissa, finally backing Fumina into a corner. But Yuuma, unable to accept that his club president is trying to win by ignoring the previously agreed rules, teams up with Sekai to destroy Miyaga's Agrissa. Thus, with the addition of Yuuma, team Try Fighters is finally formed!

The Try Fighters have achieved a splendid victory in the first round of the regional qualifiers, and they celebrate with a modest toast. But their joy is short-lived as they learn who they will face in round two. Their opponent is Seiren Technical College, a veteran team which is favored to win the championship. Whatever tactics their foes try, Seiren anticipates their moves and drives them to defeat, and thus it’s said that this team rules the battlefield. The night before the match, Fumina summons Sekai and Yuuma to the club room, where they witness a hidden feature of the Winning Gundam which may be their ace in the hole. The Try Fighters face the second round with perfect poise, but Seiren’s three Ez-SR units have analyzed the characteristics of the fighters as well as their machines, and now they strike precisely at the Try Fighters’ weakest points!

After receiving spare parts for the Build Burning from his sister China, Yuuma is on his way back to the lodging house when he runs into a gang of delinquents. Yuuma risks himself to protect the parts, and is saved when Sekai and the others come running over. Meijin Kawaguchi spots someone hiding behind a tree watching the situation and tells him to come out. The person who appears is Junya Inose, a senior pupil who once studied the Jigen Haoh school of kenpo along with Sekai and Mirai. Sekai cannot hide his shock at this sudden and unexpected reunion, and wonders why the Junya who was once so kind would resort to such dishonorable tricks. Afterwards, Mirai tells him that Junya is listed as an alternate team member from Tenzan Academy, representing Miyagi Prefecture, their opponent in the upcoming quarterfinals. To determine Junya’s true intentions, Sekai must put his own feelings into his fist and challenge him in battle during the quarterfinals.