Rinko Iori dusts display cases at Iori Models while Sei works on Gunpla. He’s surprised when Yuuki comes into the store out of nowhere. Yuuki explains that he’s going on a tour of Europe next week as Meijin Kawaguchi and says he heard from Mao Yasaka that Sei had modified the Build Strike Gundam Cosmos. In the Gunpla Battle room, Sei shows Yuuki the completed Build Strike Galaxy Cosmos, which features a new transforming backpack. Sei asks if Yuuki is going to use the Ballistic Zaku, but Yuuki instead reveals his new custom unit, the A-Z Gundam. Yuuki is impressed that Sei could discern so many of its details from a single look at it. Sei is fired up and wants to fight in a battle, which Yuuki agrees to as just a fan rather than the Meijin. The battle begins in a space level, and Yuuki flies by Sei and uses his hyper mega launcher to destroy Luna II in a single shot. Yuuki asks Sei if he’s surprised, and Sei answers that he knows Yuuki was showing him the suit’s performance since this is his first time seeing it. Yuuki presumes that Sei understands everything now about the A-Z Gundam’s performance and slicks back his hair because he intends to go all out. Yuuki opens fire, but Sei blocks with his Cosmos Shield and returns fire. Sei sees how fast the A-Z Gundam is and simultaneously activates the Star and RG Systems. Sei and Yuuki lock beam sabers and trade fire from their vulcan guns. Yuuki fires both of his hyper mega launchers, which overwhelms Sei’s shield. Sei gets knocked into Earth’s gravity well and is pulled into the atmosphere. He’s surprised when Yuuki shows up in Waverider mode to shield him from the heat of re-entry. Yuuki wants a complete victory, and the two attack each other again once they enter the atmosphere. Yuuki grabs onto Sei and plans to slam him into the ground, but Sei uses his thrusters to divert them into the ocean. Sei sees that the Galaxy Cosmos is heavily damaged and running low on Plavsky particles, but he thinks of Reiji and marches forward. Yuuki sweeps downward with his beam saber, but the Galaxy Cosmos buckles from its leg breaking, allowing Sei to dodge and cut into the A-Z Gundam’s cockpit. The battle ends in a draw, but Sei isn’t satisfied because he dodged that last attack only with luck. Yuuki comments that this is how battles are and says he wants to have another fight when he returns to Japan. Sei asks Yuuki if it was OK to break his Gunpla before going on tour, and Yuuki asks if he can borrow Sei’s equipment to fix it. Sei realizes that Yuuki intended to improve the A-Z Gundam by fighting him.
The final episode of Battlogue closes the series out by focusing on a battle between Sei and Yuuki. Set after GM’s Counterattack, this short shows just how far Sei has come as a fighter than he can bring Meijin Kawaguchi to a draw, even if by luck. The Ballistic Zaku wasn’t a particularly impressive looking Gunpla to be used by the Meijin, so it’s nice to see him use the A-Z Gundam this time. I don’t know if we’ll ever see Sei, Yuuki and the rest of the original Build Fighters cast again after this, but if not, this is a pretty good send off.