In Japan, the culture of visiting hot springs (onsen) for relaxation or health purposes is very much alive and well, and there are many devotees of the practice. But there is an even deeper layer for those in the know, who eschew the well-known onsen resorts, such as Hakone, and go in search of remote 秘湯. Written with the Japanese characters for "secret" and "hot water," these hitou are onsen that are well off the beaten path, usually hidden within the many mountain chains that crisscross Japan. While they often offer accommodations, some of the wildest ones are simply steaming pools among the trees.

Ubayu Onsen, located not far from the city of Yonezawa in Yamagata Prefecture, is one of those best loved by true connoisseurs of "secret onsen." Located above 1,300 meters in a tiny, remote valley, the wooden lodge sits in lofty solitude beneath a rocky crag, surrounded by deciduous forest. The hot springs can only be accessed from late April to early November, before the heavy snows of Yamagata Prefecture make the narrow, winding mountain road impassable. 

The springs here have attracted bathers for over 450 years, and the current owner of the Masugataya ryokan (inn) is the 17th generation to care for this remote gem. The wooden building is simple, but every surface is polished to a high sheen. The three outdoor baths, which include both women-only and traditional mixed-gender bathing pools, are a milky white with a turquoise sheen, surrounded by craggy rocks and maple trees. 

Fall is considered one of the best times to visit, as the brilliant colors of the trees surrounding the dark wooden building bring to mind visions of Arcadia or, for fans of Lord of the Rings, a wilder Lothlórien or Rivendell. As it is over 8km away from the closest station, the only sounds are those of rushing water and the wind, and there are none of the ugly electric lines that so commonly interrupt skylines in Japan. The lack of cellphone reception or wi-fi, along with the wooden suspension bridge you must cross to climb up, further emphasizes the feeling of stepping into a different time and space. 

There are a couple of hiking trails nearby, for those who want to spend an extra night and explore the wild nature of the mountain range. Just watch out for monkeys and bears!