Shima Onsen Sekizenkan is a historic hot spring ryokan located along the Shima River in Nakanojo Town, Agatsuma District, Gunma Prefecture. Founded in 1694 (7th year of the Genroku era), its main building (Honkan) is recognized as Japan's oldest existing wooden bathhouse and lodging architecture and is designated as an Important Cultural Property of Gunma Prefecture. The ryokan is also known as one of the models for the bathhouse in Studio Ghibli's animated film Spirited Away, with its iconic red bridge and atmospheric facade being a beloved symbol of Shima Onsen. The iconic Genroku-no-Yu bathhouse, built in 1930, features Taisho Romanesque reinforced concrete architecture with five stone bathtubs illuminated by natural light through grand arched windows, and is also designated as an Important Cultural Property. The hot spring water is sodium-calcium chloride-sulfate spring (neutral, high temperature) with pH 6.6 and a source temperature of 67.4 degrees Celsius, flowing at over 900 liters per minute. The colorless and transparent water is 100% natural free-flowing with no added heating, cooling, circulation, or disinfection. Shima Onsen has been known since ancient times as a spring that cures 40,000 ailments and is recognized as one of Japan's three greatest gastrointestinal hot springs. Sekizenkan comprises three buildings: the Honkan (traditional hot spring cure wing), Sanso (National Registered Tangible Cultural Property built in 1936), and Kashotei (premium wing), offering accommodation styles ranging from traditional toji therapy to luxury lodging.