Gai is the leader of the Serpent Tail mercenaries. He's a coordinator and doesn't side with either Earth Alliance or ZAFT. He only does jobs to scout, bomb, or steal mobile suit technology. After meeting Lowe, Gai befriends him after stealing Lowe's Blue Frame Astray.

Like Lowe, he believes that mobile suits have a hidden strength only the pilot can feel. But he could care less if the war ended or not, as long as he's being paid to do the right thing.