Gundam Gaia Gear is the story of the resistance group Metatron's struggle against the Man Hunting Attachment (MHA) police force of the tyrannical Earth Federation in the year UC 0203. To improve their chances of winning, Metatron creates a memory clone of the legendary Char Aznable. Char Afranche, aged 19 years, assumes command of Metatron and pilots the Gaia Gear Alpha after learning the truth of his origins.

Gundam Gaia Gear was written by Tomino Yoshiyuki and features mechanical designs [mostly] by Ito Mamoru. Gaia Gear was Tomino's first attempt to portray the 3rd century of the UC universe. Later works by Studio Sunrise have invalidated Gaia Gear and it is now considered a UC side story (when it's remembered at all). Ito's mechanical designs are innovative and hearken back to the days before the "Gundam Look" was set in stone.

Gundam Gaia Gear first appeared as a serial in the Japanese edition of Newtype Magazine (from April 1987 to December 1991). The story was then collected in five novels that ran from September 1988 to April 1992. It was also a radio drama that was collected on 5 CD's (the first released in November 1992 and the final in July 1993). Two soundtrack CD's accompanied the radio drama. Mechanical designs were featured in the February, March and April 1991 issues of Hobby Japan Magazine.