Lag's rescuer, who first appears in chapter 1. He is the letter bee that finds young Lag Seeing marked as a letter in "Coza Bel", a small town in the "Yodaka District" (The low class district in Amberground). He has to deliver to "Cambel Litus" a town also on the "Yodaka District" so he can join his aunt which was trusted to take care of him from the person who wrote Lag's letter data. Gauche is also a a caring and enthusiastic letter bee, he is trying to become the "Head Bee" (Captain of the letter bees) so he has enough money to help his sister and live peacefully.
He is said to be "missing" when Lag asks about him 5 years after their meeting. Later, he appears before Lag as a marauder, someone who snatches letters away from letter bees. While crossing from Yuusari to Akatsuki, he lost his memories after returning from "the light" alive and is renamed, Noir. Noir is always accompanied by his dingo, Roda, a human child that was fused with his previous dingo, the dog, with the same name.
After several failed attempt's of Lag to restore Gauche´s heart, in chapter 28, Lag shoots him through his heart with a heart bullet leaving him in a coma.
At the end of chapter 37 Gauche awakens but he is still Noir, although some part of him nurtures feelings for Lag and Sylvette.
Regarding Aria, his childhood friend who always loved him, Noir seems to have forgotten her too.