"This paper shows (1) that both Shinto and Bushido have rational bases for having prevailed in Japan, (2) that the norms of Shinto and of Bushido promoted the society or state-building process f the chiefdom, kingdom, and feudalism of Japan, and (3) that those societies can be formulated by a hierarchical-coalition game, and (4) that they can be classified by differences in how to share leaderships for commons' preservation, agricultural production, and enforcement services, the 'increasing returns to scale' effect of which are crucial factors for determining how or by whom those leaderships are shared."