Let's get some background on Japan's notorious Unit 731.

 

It was a top secret biological and chemical warfare research group established in the Chinese city of Harbin in the 1930s. One of the group's most infamous experiments was vivisections, in which prisoners were dissected alive, usually without anesthesia. In other tests, people were deprived of food and water to determine how long they could go until dying. Others were exposed to lethal doses of X-rays or various chemical weapons inside gas chambers. At least 3,000 people were killed at the hands of the unit. Victims included pregnant women, the elderly, children, and infants.