Quick citelet-- Tokugawa Japan, eds. Chie Nakane and Shinzaburou Ouishi, transl. ed. Conrad Totman, University of Tokyo Press, p 37: "The population at the end of the seventeenth century was approximately thirty million, and it remained stable until the early years of the nineteenth century"-- so yeah, sounds like a boom during the early/pre-Edo era. IIRC some of the early precursors to the Greater Asian-Pacific Co-Prosperity Sphere were the absorption of the formerly kinda-independent regions of Ryuukyuu (Okinawa and other southern islands) and Ezo (now Hokkaido)-- dunno how many settlers were required vs. cannon-fodder, but I suppose it doesn't make much difference in the long run.