The land of Daisokoku
The mythos behind Daisokoku states that the great Island is the body of the Great Beast, slain by the first hero that dared oppose its rampage through the fledgeling world. She was Shizuru, Empress of the Heavens. And it was Shizuru that would give the Great Beast the proper rites to be laid to rest, and for its husk to lay the foundations of a nation to be found many, many years later.
The Great Beast, and the Great Land, would later be known as Daisokoku, the compact between the first peoples to find this land in the Four Ages.
In the First Age, it was humans under their leader, an ancestor of the Emperor Himself, to have found Daisokoku, and who spread out across the bountiful plains and humid swamps. They founded settlements and villages, harvesting of the earth. Humans brought life and magic with them, and it crept in the land itself. Creatures much like humans rose in the forests to live in isolation, but they are few and far in between. Man expanded steadily throughout the Daisokoku landscape.
In the Second Age, from the far west, a swarm of black feathers and lightning came and settled on the crags and mountaintops making up Daisokoku. Crow-like beings actually lead by heralds of their gods, these were the first tengu settlers fleeing a great evil. The tengu were mostly isolated from humans, but there were great times of war and fragile moments of peace, for the tengu were both possessive and in need of land of their own.
At the dawn of the Third Age, from the west more non-humans came: creatures that were blamed to have arrived by the coming of the tengu. However, it would be learned that the rampant oni and imps and other vile beasts had come from a giant volcanic island north of Daisokoku. They fanned out to the west, and would either find land to conquer there, or return down south and eastwards into Daisokoku again. The humans banded together in their cities and provinces under the rule of their warlords, the first of daimyo. In the dark age that followed, it wasn’t until a human that was a descendant of the first settlers’ leader rose that the daimyo cared about fighting alongside each other for survival. But when that man rose and united daimyo under him, a first stand against the evil of the north could be made. The First Emperor oversaw the warring lords as well as he could, and would gather great warriors from around the land to fight the incursion from the north. Tengu of the mountains and humans of the plains joined together to seal the greatest of volcanoes in that Age, stemming the tide of evil somewhat, and so did stabalize the land.
With the Fourth Age, the warlords precided over their respective domains, and would either lead their own people or would swear fealty to the descendant of the great leader. So came about the Empire. From the Empire came hundreds of years of order. In the years of order, the seas, while dark, calmed. The Eastern seas harboured peoples and islands friendly to the peoples of Daisokoku, and the Emperors before the Emperor were wise enough to retain good ties with them. From these islands, other peoples steadily made their way onto Daisokoku. Dwarves of the underground had struck out to other isles for fortune. Elves sought to expand their horizon and worldviews, and found a great isle steeped in legend. Gnomes and Orcs found opportunity for trade side by side, as either merchants or pirates.
So for Daisokoku the Fourth Age lasts today, (mostly) under the rule of the 50th Emperor, Hiroshi the Merciful.