Plavsky particles begin materializing around the arena, so Takeshi asks Ral and Chinan to help him evacuate the crowd. Baker asks Mashita to stop the Arista, but he tells her it’s still glowing. The enormous crystal transforms into the space fortress A Baoa Qu and smashes through the ceiling. With the arena transformed into a space battlefield, Fellini, Kirara, Mao, China, Aila and Misaki run over to where Sei, Reiji and the Meijin are. Everyone starts running away, but Mashita grabs Reiji by the leg and apologizes for stealing Arista. Reiji is surprised to hear that he’s from Arian, and Mashita asks him to do something. Nils appears with Caroline and Sebastian and explains that the giant crystal has gone out of control, and not even he can predict what the outcome will be. He loads the Sengoku Astray onto the GP Base to destroy the crystal because it’s too dangerous to go in person. Reiji vows to help Nils and says he won’t run like a coward. Sei and the others agree to help Nils, and Reiji comments that they’re all fools. Reiji’s Star Build Strike is joined by Sei’s Build Mk-II, China’s Beargguy III, Aila’s Miss Sazabi, Fellini’s Gundam Fenice Rinascita, Kirara’s Gerbera-Tetra and Caroline’s Knight Gundam. The Meijin is bothered by the state of the Amazing Exia until Allan arrives with a briefcase. Rinko tells Takeshi and Ral that she can’t find Sei and the others anywhere. The team approaches A Baoa Qu and comes under attack from unmanned Mock mobile suits, which Mashita explains were supposed to debut at the end of the tournament. Fellini, Kirara, China, Aila, Nils and Caroline attack the Mocks to hold them off. However, for as many that were destroyed, even more launch from A Baoa Qu. A large beam blast from Mao’s Crossbone Gundam Maoh destroys a sizable number of Mocks. Mao fires again and blasts a hole into A Baoa Qu as a passageway. Sei, Reiji, China and Aila enter the fortress while everyone else stays behind to guard the entrance. Nils saves Caroline from a Mock, and the amount of enemies starts to become overwhelming. However, Chinan appears in his Master Gundam, followed by Ral’s Gouf R35. Ral and Chinan perform a combo attack to scoop up a bunch of Mocks in a tornado, which are all destroyed by the Chinan Kick. Kirara is shocked by how strong they are, and Fellini says that’s the true strength of the Blue Giant. Caroline thinks the tide has turned, but an enormous energy beam blasts out from the interior of the fortress. Inside, China and Aila’s Gunpla are heavily damaged by a large cannon.
Earlier, the four traveled through the fortress’ interior, but Aila sensed a change in particles as they emerged in a chamber containing a large cannon. Aila and China pushed Reiji and Sei out of the firing line, at the cost of their own Gunpla suffering damage. A group of Mocks attack them, but they’re destroyed by the Meijin’s Amazing Exia in Trans-Am mode. The Meijin asks Sei to leave it to them, and Takeshi joins them with his Perfect Gundam. He tells Sei that the crystal must be behind the cannon, so he fires his own cannon to create a path for Sei and Reiji. Sei and Reiji reach the center of the fortress, but a heavy particle storm prevents them from advancing. Sei disconnects the Build Booster Mk-II and docks it with the Star Build Strike, which activates the RG system. The Star Build Strike unleashes a Hyper Build Knuckle to destroy the crystal. After the crystal explodes, the arena returns to normal as A Baoa Qu vanishes. Nils thinks it’s a shame that the crystal is gone since it was generating all the Plavsky particles. Mashita starts to glow red and whines that he doesn’t want to return to Arian. At the last second, Baker grabs onto Mashita and is transported to Arian with him. Sei and Reiji want to have a rematch with the Meijin since he was being controlled last time. China asks if they have to do that right now, but Reiji notes that with particles disappearing, they might not be able to ever play Gunpla Battle again. The Star Build Strike is heavily damaged, so Mao and Fellini donate parts to Sei while Allan patches up the Amazing Exia with parts from the Kampfer Amazing. Kirara grabs a camera to film what is potentially the final Gunpla Battle. As they trade fire in forest stage, Reiji and the Meijin both proclaim that this is the battle they’ve waited for. Sei thanks Reiji for letting him experience a fight like this. He wanted to be like Takeshi, but he’s no good at piloting. Reiji tells Sei that he isn’t bad at all, but he loves Gunpla so much that he’s afraid to damage them. All he needs is the resolve to fight no matter the cost. Sei sees how much he owes to friends like China, Mao and Fellini. As Reiji’s gem starts to crack, he lets Sei take over the controls. Sei is able to match the Meijin’s attacks and moves in to take the winning shot, but both units stop moving as the particles disappear. Reiji begins to glow red and tells Sei to get stronger so they can fight each other someday. Reiji tries to give Sei a high five, but he vanishes. Reiji reappears on Arian and is shocked when Aila hands him the Beginning Gundam. He asks how she can be there, and she nervously says she made a wish. He doesn’t understand, so she yells at him for being slow-witted. After the tournament, Mao and Chinan keep building custom kits, while Kirara performs in concert and Allan and the Meijin help young children with Gunpla. Baker and Mashita start selling Gunpla in Arian, while Nils and Caroline recreate the Plavsky particle in space. One year later, Sei uses the Build Strike Gundam Cosmos during the Japanese qualifier for the 8th Gunpla Battle World Championship.
So ends Build Fighters, one of the strangest Gundam series there will ever be. Even as a nontraditional Gundam series, the show had the unenviable task of following after AGE, which was a major disappointment. However, by having fun and being different, Build Fighters outshines its predecessor in every way. Throughout the series, we’ve seen countless appearances from old mobile suits that no one expected to see in animation again, or be animated at all. We’ve seen the story of Sei and Reiji grow as a pair of unlikely friends, and thematically it reaches an appropriate end with Sei being able to fight on his own. Although the final battle here resembles that of other series, the tone is entirely different since no one’s lives are actually at stake. This final episode treats us to seeing some heavies like Takeshi, Chinan and Ral finally get some action, and it doesn’t disappoint. Although Reiji goes back to Arian, he’s got Aila with him, and there’s always the possibility of them returning to Earth. In a nod to the beginning of the story, the level where Sei and the Meijin fight is the same where Sei initially fought Sazaki in episode 1. In the end, Build Fighters is a love letter to Gundam and should be enjoyed as such. If you can be open-minded and not dismiss it for not being a serious war story, you’ll find there’s a lot to enjoy.