As for the 8 year period of Japanese occupation, in General it it is said the War in China was the dirtiest, most brutal and most barbaric of all War Fronts in the Asian Theatre. Japanese war crimes were abundant and have been described by many.
As for the facts on the City of Beijing however, it is generally accepted that the Japanese Rule of the City was generally softhanded, since the City had fallen without resistance and some of its citizens even accepted the occupation as a way to revive the fallen city economy. Many held jobs with japanese Companies. Anyone opposed had fled into the Inner provinces. Thus, although the Japanese installed a Brutal Military dictatorship, local Military Administrators went out of their way not to offend the City and its inhabitants, thereby avoiding the possibility of creating new enemies and stirring up a revolt.