Koaso Vineyard was founded by Yasushi Rokugawa. Rokugawa-san's ancestral roots are in Nagano, which led him to the prefecture when he first set out to grow wine grapes. His search for a suitable place to grow his most-loved Bordeaux varietals led him to Ueda, which at the time was relatively underdeveloped for wine. This move has since paid off, as evidenced by the recent interest in the sub-region amongst those looking to make wines with power in Japan.

Rokugawa-san is also passionate about advancing the image of Japanese wine not just within Japan, but also across the world. In this regard, he started and continues to operate Degustation in Tokyo, a wine bar with one of the country's widest by-the-glass selections of Japanese wines.