Ikaho Onsen

Ikaho Onsen cascades down a hillside in the Haruna mountains of Gunma Prefecture, its famous stone stairway lined with inns, souvenir shops, and ryokan that have welcomed visitors since the Edo period. The staircase, climbing steeply through the old resort town, is one of the most recognisable images in Japanese onsen culture — a living piece of architecture that has changed little in two centuries of thermal tourism.

What makes Ikaho particularly distinctive is its iron-rich water, which runs a deep amber-brown from the high concentration of ferrous minerals that oxidise on contact with air. The water emerges at 45 °C with a neutral pH of 7, and its characteristic colour and earthy mineral aroma set it apart from the clear waters found at most other Japanese onsen. Traditionally referred to as kogane-no-yu — the golden water — this iron-saturated spring has a warm, enveloping quality that feels substantial against the skin, and a long association with relaxation that continues to draw visitors to Ikaho's atmospheric hillside streets.