In 2024, the computer network prevails throughout daily life. Sora Yuuki is a 14-year-old girl. One day, she is invited to an online game "The World". After an accident in the game, the real world begins to deform.

On the planet Earthdash, its inhabitants gaze on its moon and the technologically advanced lunar city of Mooneyes with awe. Dan JD, a boy living in Rollingtown on Earthdash's surface, gets caught up in Bigfoot Basketball—a fast-paced sport played with giant Bigfoot robots.

The long-awaited new work will be screened in theaters as a medium-length animation in the summer of 2023! Along with the summer brass band competition, the ensemble contest, commonly known as "Ancon," is a place where exciting performances are held. The performance of several people in one group has a charm different from that of a competition. In order to participate in the Kyoto prefectural tournament of Ancon, a representative team is selected in the school's preliminary round. However, with over 50 members, the Kitauji High School brass band is facing a variety of problems! Will Kumiko, the newly appointed head of the club, be able to make it through the preliminary rounds? The days of struggle begin.

At the climax of the Eve Wars, on December 24 of the year AC 195, the armies of the World Nation and White Fang met in a ferocious battle. World Nation leader Treize Khushrenada was slain, White Fang leader Zechs Merquise disappeared, and Earth was saved from destruction by the intervention of the five Gundam pilots. Having witnessed the consequences of war and hatred, the people of Earth and the space colonies put aside their differences and together founded a new world government. Under this newly-formed Earth Sphere Unified Nation, a year has passed in peace. The government and the populace have disarmed themselves, and almost every remaining mobile suit has been destroyed. Deciding to follow suit, Gundam pilots Heero Yuy, Duo Maxwell, Trowa Barton, and Quatre Raberba Winner place their mighty mobile suits inside an asteroid and send them on a one-way voyage into the sun. But even as they bid their Gundams farewell, a new conflict is drawing near. 

(Source: AniDB)