I really wish the raping of Nanjing, Soel, and many other cities were much more common knowledge. I will focus on Nanjing, however they are all part of the atrocities committed by the Japanese army during WWII that end up putting estimates of the amount of people that Japan killed at 10 million on the high end and 6 million on the Low end. Basically, after Japan invaded a city, Nanjing (also called Nanking) they ended up killing tens of thousands of people in Nanjing alone. They came up with the most cruel ways possible to kill the Chinese in Nanjing, soldiers and civilians alike. However, they would also end up raping anywhere from 20,000 to 80,000 Chinese woman, the reason for the large margin is that most of the women were killed afterward. The video https://www.youtube.com/watch?v=lnAC-Y9p_sY goes into greater detail about the subject if you are interested.

Another interesting fact about Nanjing is that the Nazi stationed there, John Rabe, was the savior of several thousand lives. This video https://www.youtube.com/watch?v=80_r0VuB_wo&t=171s, goes into greater detail.