Harvesting the organs of a Kaiju is a highly profitable business in black marketeering. One of the first Kaiju harvested for their organs by harvesters was the Category II Kaiju, Onibaba, after it was killed in Tokyo by Coyote Tango.
The frequency of Kaiju organ smuggling in the black market rivals that of ivory by the year 2025. Harvesters act separately from the Pan Pacific Defense Corps, operating for others (like Hannibal Chau) or their own personal gain. However, there were instances where the Defense Corps would contract Harvesters in order to gain access to Kaiju organs and other parts necessary to conduct studies on Kaiju remains. Harvesting Kaiju organs or other body parts from the creatures is considered illegal, prompting harvesters to act quickly when excavating the bodies within an exclusion zone.