Gunpla Battle Nexus Online (GBN) is a network game that lets people have adventures with their Gunpla in a virtual cyberspace dimension. Middle-school students Riku Mikami and Yukio Hidaka recruit their classmate Momoka Yashiro and dive together into this vast world. Becoming "Divers," or inhabitants of GBN, they meet a mysterious girl named Sarah who has an amazing sensitivity to Gunpla. As they meet new friends and allies, the force known as Build Divers is born!
The story is set two years after the story of Gundam Build Divers, with a new version of the "Gunpla Battle Nexus Online" (GBN) game, and new Divers: Hiroto, a lone Diver who plays like a mercenary; Kazami, a wanderer who goes between parties; May, a mysterious solo Diver who participates in Gunpla Battles all day; and Parviz, a beginner Diver who has an introverted attitude but desires co-op play. While all four live solitary existences, they are brought together by circumstance to form a team in an experience that goes beyond GBN.