Gundam Build Divers.

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!