In a nuclear disaster, the greatest concern is whether there are any effects on human health and on living organisms from long-term, low-dose-rate radiation exposure resulting from environmental contamination caused by leaked radioactive materials. Fieldwork on the Fukushima Daiichi Nuclear Power Plant (FNPP) accident is essential to address this issue. Since the accident occurred, we have continued to investigate the effects on livestock and wild animals, and have been studying wild Japanese macaques, the species most closely related to humans, in earnest since approximately two years after the accident. Part III outlines the benefits of analyzing wild macaques and the current status of our studies.