Kusatsu Onsen Yubatake — Healing Hot Spring Field

Kusatsu Onsen (草津温泉) is Japan's most famous hot spring resort, renowned for its yubatake (湯畑, 'hot water field') — a steaming wooden channel system where 32,000 liters of 55-65°C mineral water flows per minute, cooling from volcanic source to bathable temperature. The yubatake sits in the town center, billowing sulfurous steam day and night, surrounded by traditional inns (ryokan), souvenir shops, and public bathhouses. The water is highly acidic (pH 2.0-2.1), giving it powerful antibacterial properties and a distinctive sulfur aroma.

Kusatsu's hot spring culture dates to the 12th century, and the town has preserved its onsen machi (温泉街, hot spring town) character — wooden buildings, stone paths, and the ritual of yumomi (湯もみ, water-stirring performance) where performers use long wooden paddles to cool bath water while singing traditional songs. The town is perched at 1,200m elevation in the Joshu Mountains, making it a year-round destination — summer hiking, autumn foliage, winter skiing, and spring renewal.