Who is Asaka Yasuhiko from The Rape of Nanking and what is their importance?

As one of the leaders of the Japanese invasion, as well as the relative of the emperor of Japan, Asaka held great power during the war. When Matsui was stricken with illness, he was replaced by Asaka, who not only had full power over the military of the Nanking region, but also knew Nakajima and Yanagawa, the other two leaders in the region, personally. Asaka met with Yangawa, who informed him that three hundred thousand Chinese troops near Nanking were willing to surrender.