Which spirit is associated with willpower and resides in the Kidneys?

The spirit associated with willpower that resides in the Kidneys is Zhi. In Traditional Chinese Medicine (TCM), Zhi is often translated as "will" or "willpower," implying determination, drive, and the ability to pursue one's goals. The Kidneys are considered the foundation of Yin and Yang, and they are also responsible for storing essence (Jing) in TCM; Zhi is closely linked to the vitality and strength that comes from this essence.

In contrast, Shen corresponds with the Heart and represents the mind, consciousness, and spirit. Hun is associated with the Liver and is linked to the ethereal soul, creativity, and dreams. Po, related to the Lungs, encompasses the corporeal soul and is tied to the physical body and its instincts. Each of these spirits plays a distinct role in a person's psychological and spiritual health, but it's Zhi that specifically epitomizes willpower and is attributed to the Kidney's function in this context.