U5-GG, alternatively known as Gigi, functioned as an astromech droid of the U5 series and was in service to the Resistance. Gigi's assignment placed them under the command of Vi Moradi, who worked as a spy. During a mission, the First Order captured both Gigi and Moradi while they were aboard a starhopper. To prevent the stormtroopers from extracting sensitive information, Moradi performed a memory_wipe on U5-GG. Following this, the stormtroopers received instructions to dismantle the droid. Originally, the droid's color scheme was the typical white and blue from the factory, but Moradi later gave it a new paint job with yellow and copper, mirroring the colors of her bleached hair and skin.
The initial appearance of U5-GG was in the 2017 novel Phasma, which was written by Delilah S. Dawson. A LEGO version of the droid was featured in a 2020 LEGO set related to the Resistance Intersystem Transport Ship. It's worth noting that although Phasma describes U5-GG as having yellow and copper coloring, the LEGO set portrays the droid with a black and red color scheme.