Doctor Shiro Zama (played by Robert Ito), also known as Takeo Ishimaru, was the commander of an elite section of the Japanese medical corps known as 731, a unit that had experimented on human subjects, performing vivisections without anesthesia, testing frostbite tolerance levels on infants, and exposing war prisoners to disease, but its scientists were never brought to justice. This doctor was believed to have died in 1965, but had actually come to the United States and continued his work under the name Shiro Zama. The Syndicate employed him and his colleagues in their hybridization experiments as part of the colonization project. These experiments involved gene therapy hybridization performed on the homeless and insane who were later taken by Doctor Zama to the Hansen's Disease Research Facility, where the gene therapy effects (burns and a half-human, half-alien physiognomy) was believed to be leprosy deformity, although the colony's original patients were aware of the difference.
Doctor Shiro Zama was also involved in the medical procedures performed on female abductees to generate superovulation and harvest their ova for hybrid production, leaving them sick and barren. The insertion of their chip implant was also Doctor Zama's doing. (TXF: "Nisei")