Tucked into a quiet mountain valley along the Ichinomata River, a tributary of the Awano River in Toyota-cho, Shimonoseki City, Yamaguchi Prefecture, this lone inn of Ichinomata Onsen is known as the Hidden Retreat of Kanmon. Surrounded by mountains on three sides, the spring is an alkaline simple sulfur hot spring with a remarkable pH of 10.0, the highest alkalinity in western Japan. Its silky, lotion-like texture has earned it a reputation as a super beauty bath. Although the source emerges at a relatively low 28.6 degrees Celsius and is therefore heated, the water is served free-flowing source-fed style and lavishly fills every tub. With more than a century of history since its opening, the spring has recently been selected among the Top 10 Hidden Hot Springs of the Chugoku Region. The setting offers four seasons of mountain village beauty: fresh greenery in spring, fireflies dancing along the river in early summer, brilliant autumn foliage, and snow-covered scenery in winter. The bathing facilities include the main Beauty Skin Bath, a cypress bath, and an open-air bath. A winter specialty of wild boar hot pot, made with fresh game from local hunters, is also a beloved highlight. With 22 guest rooms, the Hotaru-bi no Yado (Inn of Firefly Light) offers tranquil seclusion and rustic mountain cuisine deep within the Kanmon back country.