Kashi Onsen Ryokan Daikokuya is a secluded single-inn hot spring (ichiken-yado) nestled in a mountain gorge within Nikko National Park in Nishigo Village, Fukushima Prefecture, along the headwaters of the Abukuma River surrounded by primeval beech forest. Founded in 1384 when the Buddhist monk Shuan discovered the spring in the zodiac year of Kashi (Kinoe-ne), the onsen boasts over 640 years of history. During the Edo period, the influential feudal lord Matsudaira Sadanobu of the Shirakawa domain loved this spring and built a villa called Shokkatei, which still stands today as a designated cultural property and is used as a guest room. The signature attraction is the Oiwaburo (Large Rock Bath), a spectacular 150-year-old mixed-gender communal bath measuring 5m by 15m with a depth of 1.2m. Hot spring water naturally gushes from the bedrock at the bottom, creating a gentle soothing temperature perfect for prolonged standing-style bathing (tachi-yu). A fertility stone (kodakara-ishi) sits at the center of the bath. The inn has two source springs: Source 1 is a calcium-sodium sulfate spring (pH 7.6) and Source 2 is a simple hot spring (pH 7.8), both flowing at 100% natural with no additives. The colorless and transparent water has a beautiful bluish-white clarity reminiscent of a mountain stream. The main building was reconstructed in 2009 with modern amenities while preserving the traditional atmosphere. A member of the Japan Association of Secluded Hot Spring Inns.