The Panda King makes his first appearance in Sly Cooper and the Thievius Raccoonus..
The Panda King has a history with Sly, as Panda King was a part of the original Fiendish Five, a an evil group of villains that all took part in stealing the Thievius Raccoonus and killing Sly's parents. Sly and the Gang travel to China in an attempt to take down the Panda King.
As a child, Panda King was always amazed by the fireweorks he saw being set off around his hometown. He then studied the art of fireweorks, becoming a pyrotechnician. He then attempted to offer his fireweorks to the noblemen who set the fireworks off each year. However, the nobleman saw the Panda King as a poor, low class being and rejected his work. This humiliated and greatly angered him, causing him to seek revenge and destroyed villages all over the country using his pyrotechician skills. This detruction was noticed by the Fiendish Five, who recruited the Panda King as their demolitions expert.
The Panda King battles Sly in Sly Cooper and the Thievius Raccoonus, using his signature fighting technique, known as "Flame-Fu". Sly ultimately gets his revenge and defeats the Panda King, and retrieves another piece of the Thievius Raccoonus. Later on, in Sly 3: Honor Among Thieves, the Cooper Gang are in need of recruiting more members to their gang to achieve their goal. Bentley ultimately suggests none other than The Panda King. Sly is understandably reluctant and refuses this idea initially. However, he ultimately agrees in the end, and he and The Panda King not only join forces, but they make a truce.