The Tale of Yokohama
During a time when the Shogunate of Yokohama was at its weakest, up in the northern reaches of the country rose a particularly ruthless warlord, a man hellbent on taking both heaven and earth for himself, or at least as the rumors say. Over the course of only a few years almost the entirety of northen Yokohama was trapped under the warlord's cold, iron boot singularly known as Hashimoto.
In interest of saving themselves from the ravenges of total war the remaining free daimyos agreed to a pact, a coalition, giving rise to The Shinma Coalition.
Geography:
The country of Yokohama: the Northern country of Hashimoto, the Southern country of Shinma (The Shinma Coalition), and the ravages between them.