The document also recorded that four members aged 15 to 21 were sent to a Harbin-based medical university in the puppet “Manchukuo” for three years of “medical training” as military family students.”This is key information showing the joint training of young soldiers by the Japanese military, government and medical institutions, and once again proves that the implementation of human experiments and germ warfare was a top-down, organized, premeditated, and systematic group crime of Japanese militarism,” said Jin Chengmin, curator of the exhibition hall.Unit 731 was a top-secret biological and chemical warfare research base established in Harbin as the nerve center for Japanese biological warfare in China and Southeast Asia during World War II.At least 3,000 people were used in human experiments by Unit 731, while more than 300,000 people in China were killed by Japan’s biological weapons.