Aoni Onsen is a secluded hot spring inn nestled deep in a forested valley of the Minami Hakkoda mountain range in Kuroishi City, Aomori Prefecture, nationally known as the Lamp Inn. The history began in 1928 when Yogaku Niwa, a poet from Kuroishi, built a cabin to recover from illness, and it opened as a hot spring inn in 1929. In 1931, when the entire remote area lacked electricity, the inn started using kerosene lamps for illumination. Although power lines were eventually installed, the supply was intermittent, so the owners decided to continue using only kerosene lamps. Even today, hundreds of oil lamps light the guest rooms and bathhouses, earning the establishment its famous nickname. The Aoni Stream flows from the Minami Hakkoda mountain range, and the inn is surrounded by virgin forest, waterfalls, and rapid currents in a naturally rich valley. The hot spring has four baths, all with natural flowing spring water: Kenroku-no-Yu, Main Building Indoor Bath, Takimi-no-Yu, and an Open-air Bath (mixed bathing with ladies-only time available). Takimi-no-Yu and the outdoor bath can be accessed by crossing a suspension bridge to the opposite bank. The spring quality is simple hot spring water, colorless and transparent with a gentle feel on the skin. Accommodation facilities include the main building, water mill building, and three separate cottages, all Japanese-style rooms with a total capacity of 100 people. There are no TVs or electrical outlets, and mobile phones cannot be used due to no signal, offering a complete digital detox experience. Only body shampoo is available in baths (no shampoo or conditioner), and hair dryers cannot be used. During the winter season (December 1 to March 31), private vehicles are prohibited from Route 102 entrance to the inn, and guests must use the free shuttle bus (reservation required) from Nijinoko parking lot.