Haru Irei, who witnessed the first lighting of the 1/1 scale RX-78-2 Gundam in Odaiba, becomes inspired to build Gunpla. Gunpla which is a portmanteau of Gundam Plastic. Haru purchases a one of a kind gunpla, the GPB-X80 Beginning Gundam. After building the kit, Haru, now a Gunpla Builder, and the Beginning Gundam enter the virtual world of Gunpla Battle, where players can pilot their customized Gunpla in team matches or one-on-one fights. Haru must rely on the support of his friends if he is to become a Gunpla Battle Champion and attain the rank of Gunpla Meister.

Kinta Tokumaru is a young swimmer who wants to join the prestigious Ochiai High School swimming club. However, on his way to the club, he is caught up in Ultra's wild behavior and realizes that the team doesn't even practice. Frustrated, Kinta challenges Ultra to a match in order to train together, but is defeated by Ultra's swimming ability. Kinta is at a loss, but he learns that the swimming club's activities have only been suspended, and all the members have a strong passion for swimming. At that moment, Ultra, who had seen through Kinta's qualities, invites him with a promise: "Let's go to the Olympics together."

Tochino Arashi, who is treated as a heel sumo wrestler due to his arrogant personality, continues to win consecutive victories and is finally promoted to yokozuna. However, that night, he suddenly switches with a boy named Makoto Akagi, who threw himself off the bridge because of the bullying. Although Tochino has become frail, he learns the joy of confronting a formidable opponent by being hit by the rough seas of the Hanayama High School, where Makoto used to go to.