Domon is the selected representative of Neo Japan for the 13th Gundam Fight. He accepts this task because he's in search of his older brother, Kyoji Kasshu, and to free his father from suspended animation. He trained under the great martial art master, Master Asia who won the 12th Gundam Fight. He first piloted the Shining Gundam, but it suffered massive damage, so the Neo Japan space colony sent him the God Gundam (Burning Gundam in the English version) so he could still go on in the Gundam fight.

After his training with Master Asia, he is bestowed the title of King of Hearts, a name used by the Shuffle Alliance. Now, Domon wants to find Kyoji and the mysterious Devil (Dark) Gundam, set things right, and win the Gundam Fight for Neo Japan.