Yin-Yang was a villain who appeared in "Feng Shui Is Like Sooo Passe" with a secret hideout on a Southern island with (Feng Shui) henchmen, along with a quicksand trap or secret entrance to sink or capture the spies in his lair, telling them his objective of being able to move the continents and balance the globe into a yin yang image, although the pressure would eventually cause the entire world to be destroyed. To do so, he arranged to be Jerry Lewis's guru to distract him and WOOHP to make sure his objective became a reality.
He had a camera on the back of his neck that transmitted information to his contact lense, giving him a 360 degree view.
- His name is a reference to yin and yang.
- The title of the episode he appears in is a reference to Feng shui.
- His ship was based on the Sea Shadow (IX-529).