Japan is an endless chain of countless volcanic islands, small except for four, stretching from subtropic to Arctic waters, with matching biological diversity, enhanced by immigration when connected with the continent, also allowing human immigrations, first from Siberia the Ainu hunter-gatherers, later from Korea the Mongoloid majority that supplanted them south of Hokkaido. Scarcity of agricultural land encouraged marine orientation. It feudal history culminated in the shogun reunification and isolation, still preserving many unique customs despite major imports ...