World War II was the greatest conflict in human history in matters of intensity, financial and human resources mobilized, and the number of victims. Throughout the six years of conflict, violence spread across different continents, resulting in the death of approximately 70 million people. Major highlights of World War II were the construction of concentration camps by Nazi Germany, especially in Poland, which aimed at enslaving and exterminating Jews, Gypsies, Jehovah's Witnesses, homosexuals and so on. In addition, during the Second World War, atomic weapons were used for the first time, launched by the US against the Japanese cities of Hiroshima and Nagasaki.
During World War II, Japan, driven by its xenophobic nationalism and its radical militarism, committed a series of war crimes. One of the places where several people were victims of the brutality committed by the Japanese army was the facilities of Unit 731. This unit was created under the name of "Kwangtung Army Water Supply and Epidemic Protection Unit" and had as its primary function to control of water quality used by the Japanese army based in China. However, Unit 731 was secretly used by the Japanese Army to promote a series of macabre studies on living human guinea pigs and to promote studies for the development of chemical and biological weapons.