Inferno of the Living
Sekai is the middle of the Three Planes, between Jigōku and Tengoku. According to some legends, it was created by the emperor Sekaijin, just as his brothers Jigōjin and Tengojin created Jigōku and Tengoku. According to other legends, Sekai existed before the three divine brothers, created by the old gods — the spirits of the plane’s islands, forests, mountains, and seas. In those legends, Sekaijin founded the Yokai Empire, built the imperial capital city-island of Washū, bound the plane to the axis, connecting it to Jigōku and Tengoku, and helped his brothers establish the celestial order.
Sekai is a world covered by ocean, with archipelagos of islands across its surface claimed by the various yokai clans and their daimyo. Those daimyo owe allegiance to the divine emperor Sekaijin. Beyond the empire, however, other clans of yokai live with their own customs and languages, in defiance of the empire.