After viewing the RX-78-2 Gundam statue in Odaiba, Haru Irei picks up the HG 1/144 GPB-X80 Beginning Gundam kit and discovers its potential by joining a Gunpla Battle.
Haru wins his first Gunpla Battle, but is swiftly defeated by the mysterious fighter Boris Schauer and his GPB-X38-30 Forever Gundam. Learning from his loss, he makes improvements to his Beginning Gundam before returning to Gunpla Battle.
Haru receives a new set of parts to upgrade his Beginning Gundam before he, Kenta, and Rina advance to the Gunpla Battle finals, where he faces Boris one more time.