Domon Kasshu is a fictional character in the anime and manga G Gundam.

Domon Kasshu tough and silent pilot of Neo Japan , who was once trained by the great martial artist, Master Asia , and was made the new King of Hearts. Now that the 13th Gundam Fight begins, the pilot however has other things in mind, to seek out Kyoji Kasshu , his brother. Years earlier, the Kasshu family was found working on a said "evil machine" known as the Dark Gundam (the Devil Gundam in the original Japanese). Domon found out that Kyoji was behind it all and stole the Devil Gundam and headed for Earth. Domon's mother was killed in the conflict and Doctor Kasshu, Domon and Kyoji's father was sentenced to a frosten state for constructing the Devil Gundam. Domon enters as Neo Japan's pilot only to find his brother and make him pay for he had done.

After many victories against many of the world nation's pilots, Domon and his partner Rain Mikamura arrive in Tokyo to only be confronted by an Army of the Devil Gundam. Though Domon and Rain make an attempt to escape, it seemed like the end, but the appearance of a mysterious stranger, who happened to be Domon's old martial art teacher Master Asia comes to their aid. After making short work of the Dark Army, Domon tells Master Asia about what happened to his family and why he became a Gundam pilot. Shortly after a moment of peace in the ruined city, a massive army of the Devil Gundam begins its attack on Tokyo. Domon joins Master Asia and his small band of pilots in the conflict and manages to save the city. But something is not right and it appears that Domon's master has joined the Dark Gundam, saying that the Devil Gundam's three special theories are what this world needs in order to be revived.

Master Asia attacks his former student, but is stopped by the peacekeeping forces known as the Shuffle Alliance , that have been watching the Gundam Fight. After making a short recovery, Domon is wanting to know why his master betrayed him, and sets out to meet him. As Domon and Master Asia meet, the Devil Gundam rises from under Tokyo and Domon is confronted by four pilots, who he had fought, Neo America's Chibodee Crocket, Neo China 's Sai Saici , Neo France 's George de Sand , and Neo Russia 's Argo Gulskii . These pilots were infected by DG Cells , and were stronger than they were last. The Shuffle Alliance once against came to Domons aid and during the fight, they realize that they where destinied to be the new Shuffle Alliance , and gave their lives for the sake of the four pilots. After the death of the Shuffle Alliance, Domon actives his Shining Gundam 's super mode and able to make Master Asia retreat for the time. In the process of the Devil Gundam, a stranger, known only as Neo Germany 's pilot Schwarz Bruder , who in someway helps train Domon for the coming battle with Master Asia and the Devil Gundam by convincing him he is not ready yet. So Domon goes to the Guyana Highlands where he origally trained with Master Asia. With Schwarz's help the other members of the new Shuffle Alliance are convinced to train as well.

In the final battle Domon stays behind while the rest of the new Shuffle Alliance head to Neo Hong Kong where the finals are and Neo-Russia's Nastasha Zabigov took a sickly Rain with her promising she would provide safe passage for her. Domon is able to defeat the Devil Gundam but Master Asia in anger damages the Shining Gundam. Luckily Rain contacted her father and they sent the God Gundam (Burning Gundam in the English Version) the Gundam the Neo-Japan Government were saving for the finals and with Rain's help the new God Gundam was given Shining Gundams battle data.