Maruse Shuzoten Brewery, established in 1870 and located in Nakano City, Nagano Prefecture, brews a sake called "Ikioi Masamune", which translates to “Vigorous Masamune.” True to its name, the sake is inspired by the image of dynamic energy and progress. The name comes from the legend of a carp swimming upstream and leaping over a waterfall, symbolizing success and advancement in life. One of the brewery’s most distinctive features is its use of a traditional Japanese brewing method known as "mochi-gome yondan shikomi"—a four-stage brewing process that includes a final addition of sweet sake made from glutinous rice. This unique step is added to the standard three-stage brewing method. Thanks to this technique, Ikioi Masamune is characterized by a soft, gentle texture from the glutinous rice, along with a rich and mellow flavor that sets it apart.