Heisuke Yanagawa (柳川 平助) was an IJA Lieutenant General who commanded one of the main armies in the Battle of Nanking. He would have been one of the generals photographed marching into Nanking. I've read in a few places that his photos and news references to him were censored during this time, so that he became known as "the masked shogun". For example, this excerpt from Iris Chang's The Rape of Nanking:
A third force traveled further south of Matsui's men and swerved northwest toward Nanking. Heading this force was Lietenant General Yanagawa Heisuke, a bald, short man with literary interests. Perhaps to a greater degree than most other Japanese involved in the Rape of Nanking, his life during the invasion is veiled in mystery. According to his biographer, Sugawara Yutaka, the fascist clique that took control of the Japanese military had expelled Yanagawa from their ranks because he attempted to stop their 1932 coup. After his marginalization and demotion to the reserves, Yanagawa served as a commanding officer in China and performed "great military achievements...including the surrounding of Nanking," but the military withheld his name and photograph from publication at the time. Thus Yanagawa was known to many in Japan as "the masked shogun."
Is this true? I could not find any censored photos or articles of him, and the primary source for this claim - Sugawara Yutaka, Yamatogokoro: Fukumen shogun Yanagawa Heisuke Seidan - doesn't seem to be on the internet.
Another claim I'd like to verify is the reason, which is that although he was a member of the Kōdō-ha faction, he didn't support their coup so the censorship was a form of payback. I'm skeptical of this as the faction largely disappeared following another failed coup in 1936, and Yanagawa was forced into retirement as part of the purge, only to be brought back during the Second Sino-Japanese War.