Located in the center of Kumamoto Prefecture, Kosa Town in Kamimashiki District is a town rich in nature, with the clear Midorikawa River flowing north to south. Blessed with natural blessings such as lush mountains, clean rivers, and fertile soil, the town has developed primarily around agriculture. Much of the town lies within the Kyushu Mountains, at a high elevation. Every year, the Midorikawa River is bustling with visitors for sweetfish fishing. Kosa Town also offers tourist courses that trace the history of the town, which grew along the Midorikawa River. These courses include a historic site tour that passes through Kosa Shrine, Unose Weir, Yano-no-Himon Gate, and the ruins of Jinnouchi-yakata, as well as a course that descends upstream along the Otome Plateau on the left bank of the Midorikawa River and stops at the Asohara Osmanthus, a nationally designated natural monument.