Assault of the Four Evil Kings! Gundam Heaven's Sword is the forty second episode in Mobile Fighter G Gundam.
With the help of Sai Saici and Argo, Domon defeats Michelo and heads for the next Heavenly King, Grand Gundam. Meanwhile at the hospital it is revealed the Devil Gundam was intended to restore the Earth. However Dr. Mikamura became jealous of Dr Kasshu's work and betrayed him and his family to Ulube to get its power. When Ulube arrived to take the Gundam and use it for the military, Kyoji's mother died trying to protect her son. Kyoji took the Gundam to Earth where its programming was damaged and it captured Kyoji. However, he managed to make an android of himself to guide his younger brother Domon. Ulube used Domon and Rain to find the Devil Gundam.