On the eve of the Yajima Stadium's grand ceremony, Nils Nielsen gathers Sei Iori, Meijin Kawaguchi, and their companions for a showcase duel featuring his innovative large-scale battle system. As Sei unveils his enhanced Build Strike Cosmos for the exhibition, a crucial component catches his attention. Simultaneously, an unknown force commandeers the stadium's controls, trapping Sei and his allies within. A cryptic faction emerges, poised to engage them in a high-stakes Gunpla Battle showdown.