Shortly after the television series New Mobile Report Gundam Wing ended in Japan, this 3 episode video series was released as a sequel/prequel that expanded upon the story told in Gundam Wing and also definitively ended it. In 1998, the 3 episodes of Endless Waltz were edited into a theatrical motion picture, with new footage added.

Endless Waltz begins in the year AC 196, one year after the Earth Sphere Unified Nation was formed and peace was established on Earth and among the space colonies. With there being no more war, the Gundam pilots see no need for their mobile suits anymore, and at Quatre's suggestion, all of them except for Wufei send their Gundams into the sun to be melted.

However, during an official visit to Colony X-18999, Relena Darlian, vice foreign minister of the Earth Sphere Unified Nation, is kidnapped by the Mariemaia Army, led by Mariemaia Khushrenada (daughter of the late Treize Khushrenada) and Dekim Barton of the Barton Foundation. At this time, Colony X-18999 declares independence from the Earth Sphere Unified Nation, as well as declaring war against it. Mariemaia and Dekim Barton plan to carry out Operation Meteor, which involves dropping Colony X-18999 onto the Earth. Unknown to the rest of the mankind, Colony X-18999 has been building mobile suits and prepares to attack Earth with them. Also joining the Mariemaia Army is Gundam pilot Chang Wufei and his Gundam Altron. It seems that even with widespread peace, Wufei could not turn down an opportunity to fight again.

With all machines of war now destroyed in the name of peace, the Earth's only hope rests in the group known as Preventer, staffed by Sally Po, Lucrezia Noin, and Lady Une. The Gundam pilots help Preventer by doing what they can without the use of their Gundams. Zechs Merquise also returns, seemingly from the grave, piloting the Tallgeese III and asking to join Preventer.

In addition to finishing off the saga of Gundam Wing, Endless Waltz also features several flashback sequences which give more background on each of the Gundam pilots, the colonies they came from, and the scientists who built the Gundams.