Cao was a General of the Chinese forces that were occupying Kyushu at the time when Atsushi Sawasaki declared freedom on Japan.
Cao was present during the invasion of Kyushu by the "Japanese Government" acting as a General for the invading army though it is reported that he is acting as a Humanitarian Watchdog and so it did not break the Treaty of Manila. However, he is without a doubt acting as a General for the false Japanese Government.
During the battle, Suzaku Kururugi using his Lancelot was able to break through and attack the base. In response, Cao and Sawasaki send waves of Gun-Ru after Suzaku in order to destroy him. Suzaku is barely to hold off many waves before finally running out of energy and was about to be killed. Zero (Lelouch vi Britannia) manages to save Suzaku from being killed with his Gawain and gives him a spare energy filler and both decide to decide to go after Sawasaki shocking him and Cao. They managed to take down the two's all forces and were captured. After the Battle of Fukuoka Base, Cao is exiled back to the Chinese Federation and afterwards, it is unclear to what happened to him.