Gundam Build Fighters: GM no Gyakushuu

As the grand opening of Yajima Stadium approaches, Nils Nielsen gathers Sei Iori, Meijin Kawaguchi, and their friends for an exhibition battle to showcase his innovative large-scale battle system. Excitement fills the air as Sei prepares to demonstrate his enhanced Build Strike Cosmos, but he soon realizes that something crucial is absent. Their friendly competition takes a sudden turn when an unidentified group seizes control of the stadium's systems, trapping Sei and his companions inside.

Confronted by this enigmatic team, the group must rise to the challenge of an unexpected Gunpla Battle. With their skills and strategies put to the test, the stakes are higher than ever as they navigate both the thrill of competition and the mystery surrounding their captors. The clash of creativity and technology unfolds in an exhilarating showdown that will push them to their limits.