Ключевые слова: acidic nature, akita, bathhouse, bathing, efficacy, fumarole, geothermal, gush, gush volume, hell, hell valley, highly acidic, hokutoseki, hot spring, hot spring cure, hot spring flowers, hot spring water, hot water, hydrochloric acid, japan, japans best, lingering snow, natural onsen, natural rock bath, onsen, onsen bathhouse, onsen therapy, radium hot spring, rock bath, senboku city, snow, source, spring quality, steam, stimulation, sulfur, tamagawa, tamagawa onsen, thermal therapy, virgin forest, volcanic gas, volcano, yunokawa,