It's said that a culture is reflected in its vocabulary. The Japanese onsen tradition is a case in point: the word means "hot springs" but involves a whole range of experiences. There are indoor baths (notenburo), outdoor baths (rotenburo), men-only baths (otoko-yu), women-only baths (onna-yu) and mixed-gender baths (konyoku). It turns out there is even a Japanese expression for the power of hot springs to melt the barriers between people: hadaka no tsukiai, or "naked companionship."
When I arrived in Tokyo for the first time last May, my vocabulary was limited to hai, or "yes." I had come to visit friends, but after five days of humidity, packed subway cars and the neon-lit crowds in the upscale Ginza shopping district, I was wiped out. When my friend Yukari, a Japanese journalist, suggested we head to a remote rural hot spring and its adjoining ryokan (guesthouse), I said hai.
Early on a Saturday morning, Yukari, her husband, Patrick, and I pulled on our hiking boots and headed north on a local train. Outside the window, the high-rises of Tokyo dwindled into suburbs and the suburbs morphed into forests of tall, straight pine trees. The train flashed by small villages, with their two-story concrete houses and well-tended rice paddies. From Kinugawa, a popular resort town known for its hot springs, we caught a bus that wound along twisting, narrow mountain roads for an hour and a half before finally dropping us off in a parking lot surrounded by thick forest.
As the bus pulled away, I was reminded of how rugged Japan really is. Barely 12 percent of it is flat enough for farming. The rest is mountains, most of them volcanoes that rumble to life hundreds of times every year, sending tremors large and small through the California-size island nation. All this volcanic activity fuels thousands of natural hot springs that bubble out of the ground from Hokkaido in the north to Kyushu in the south. "These geographical circumstances make the Japanese one of the most onsen-loving people in the world," Toshi Arai, an official at the Japan Ryokan Association in Tokyo, told me.
For centuries, the springs, and the reputed healing power of their sulfurous water, have drawn Japan's citizens. Legends report samurai warriors soaking off the aftermath of battle and peasants trekking to famous onsen to heal cuts and burns. In the past century, onsen have become almost synonymous with Japanese tourism. When Japan began to modernize in the late 1800s, trains made it relatively easy for city dwellers to travel to the countryside, and traditional-style inns called ryokan sprang up around the onsen to meet the needs of vacationers. When the nation's economy boomed in the late 1950s, couples and families alike flocked to the inns. Today, there are more than 50,000 ryokan in Japan; the largest have hundreds of rooms and resemble high-end hotels.
The onsen to which we were headed, called Teshirosawa, was far more modest. The attached ryokan has only six rooms. Even getting there is a pilgrimage of sorts. Situated in a national park, Teshirosawa is inaccessible by private car. Guests generally must trek five miles along a rushing river and then through a beech and bamboo forest that is home to troops of wild monkeys.
After a few hours hiking through the forest—and several stops to watch large gray macaques (snow monkeys) peer warily back at us from thickets of bamboo—we finally crested a small hill. Teshirosawa's ryokan is an unassuming, one-story building nestled in a breathtaking valley. It was founded in 1935, when a Tokyo shopkeeper discovered the spring while on a hunting trip and spent his fortune setting up the onsen and inn deep in the forest. Mountains soar straight up hundreds of feet on all sides, their slopes so steep they are almost cliffs. The air is cool and clean.
I left my boots at the front desk (I wouldn't see them again until I checked out). Sliding open a traditional door made of paper and varnished wood, I dropped my backpack onto tatami mats in a huge bedroom. On my way to the room, I had noticed some trout swimming in a tub by the ryokan's back door. I'd see them again at dinner, fried whole and served with soba noodles and fiery, pickled wasabi greens.
Before I headed outdoors, Patrick gave me the rundown. Onsen aren't places to get clean—you wash before you submerge, using soap and buckets of water. And swimsuits are considered unsanitary. Guests bring small towels (think of a dish towel, cut in half) to dry off with afterward, and that's it. The water can be hot; Teshirosawa's approaches 109 degrees Fahrenheit, and owner Miyayama Chihaka says foreign guests sometimes complain about it.
To walk from my room down the hall to the onsen, I pulled on a lightweight cotton yukata (traditional kimono-style robe) that barely reached my knees. As I folded up my tiny towel and set it on the side of the onsen, three Japanese men in the water smiled at me. "Konnichiwa!" ("Good afternoon!") one said. I smiled back and gingerly lowered myself up to my neck in the scalding water. One of them, it turned out, spoke some English. "Where you from?" he asked.