温泉文化と入浴マナー — 名湯巡りの楽しみ方

Japan is one of the world's foremost volcanic countries, an onsen superpower with around 3,000 hot spring towns and around 27,000 source springs nationwide. Since ancient times, people have used hot water immersion to heal the body, calm the mind, and even treat illness through long-term hot spring cures (toji).

Onsen in Japan are strictly defined by the 1948 Onsen Law. Legally, onsen refers to "warm water, mineral water, steam, or other gas (excluding natural gas mainly composed of hydrocarbons) that gushes forth from underground" with a source temperature of 25°C or more, or that contains specified components (carbonates, sulfur, iron, etc.). In other words, even water below 25°C can be recognized as onsen if specific components exceed the standard values.

Spring quality is classified into 10 types based on contained components. Representative ones include: sulfur springs (characterized by a rotten-egg smell, effective for sterilization and skin diseases), simple springs (few components, gentle on skin, suited for beginners), sodium-chloride springs (high salt content, called "hot water" for high heat retention), and bicarbonate springs (called "beauty water" for making skin smooth).

Japan's representative onsen towns are scattered across the country. Kusatsu Onsen in Gunma Prefecture is famous for its strongly acidic water and the "yubatake" hot water field, with the "yumomi" water-stirring demonstration as a tourist specialty. Beppu Onsen in Oita Prefecture boasts the nation's number-one ranking in both gushing volume and source count, with many "hell tour" sightseeing spots within the city. Dogo Onsen in Ehime Prefecture is one of the oldest onsen with 3,000 years of history, appearing in Natsume Soseki's novel "Botchan."

Kurokawa Onsen in Kumamoto Prefecture has gained popularity for its unified streetscape that takes advantage of the village-mountain atmosphere and its "nyutou tegata" (a pass that lets you bath-hop through three inns). Noboribetsu Onsen in Hokkaido has the steam-vent zone called Hell Valley as its source and is a rare place where you can experience nine types of spring quality in a single onsen town.

To enjoy onsen, you must observe strict etiquette as a communal space. First, you must wash your body and acclimate it to the water with a "kakeyu" pre-rinse before entering the bath. The correct procedure is to pour hot water over the hands and feet — far from the heart — first, gradually warming the body. Second, wearing a swimsuit is prohibited; in principle you go fully naked. Third, soaking your towel in the bath water is prohibited — you place it on your head or on the edge of the tub.

Historically, due to associations with organized crime, many onsen facilities have prohibited bathing for those with tattoos. Currently, in response to the increase in foreign visitors to Japan, the number of facilities that allow bathing if small tattoos are hidden with adhesive covers, or that fully permit tattoos as "tattoo-friendly" inns, is increasing. It is safe to check in advance via the official website or by phone.

Onsen are in many cases experienced as integrated with the accommodation facility called a ryokan. When you arrive at a ryokan, you are first given a yukata, sash, and haori jacket, and a standard way to enjoy yourself is to walk around the inn and onsen town in yukata. Dinner offers kaiseki cuisine, with multi-course items making use of local ingredients served in order. After the meal you bathe again, and gaze at the starry sky from an open-air bath before bed — this is the true pleasure of a Japanese ryokan.