There is currently an acute lack of information on the activities of Japanese doctors during World War II. Being a country with limited natural, financial, and human resources, Imperial Japan considered biological and chemical weapons one of the most promising and effective means of warfare in its quest to dominate Southeast Asia. In the mid 1920s, the Japanese leadership approved biological and chemical warfare research. The implementation of the biological weapons project, including human testing, was entrusted to Shiro Ishii and a group of Japanese scientists under his leadership, as well as to military and civilian experts. These studies examined the effectiveness of plague, gas gangrene, cholera, anthrax, and other pathogens. Experiments, including detailed descriptions of the subjects suffering and the results of autopsies/vivisections, were carefully documented. Field tests involved the distribution of contaminated food and crops to the Chinese population, as well as the contamination of water supplies. Similarly, in keeping with military interests, the effectiveness of munitions and the effects of decompression, hypothermia, and electric current were investigated on prisoners. After the end of World War II and the surrender of Imperial Japan, large-scale buried victims of experiments were found on the territory of the Peoples Republic of China, including the borders of the USSR. The paper focuses on the ethical component of the studies conducted, based on the dominant view in the Japanese society that all actions for the glory of the country and the emperor are justified and the absence of any ethical considerations due to the prejudice of the Japanese against foreigners in general and the Chinese in particular.