Hirauchi Kaichū Onsen, a Seaside Bath Where Hot Spring and Ocean Waters Meet

Screenwriter Kundō Koyama advocates for the recognition of yudō, the ‘way of the bath’, alongside sadō, the way of tea, and kadō, the way of flowers, as a fundamental element of traditional Japanese culture. He immerses himself across Japan in different types of baths, from hot springs (onsen) to public bathhouses (sentō), as well as domestic bathtubs. In each issue of Pen, he records these journeys in his ‘Bath Chronicle’.

Have I ever had a bathing experience as unforgettable as this one? Moonlight stretched across the night sea like a luminous path, drawing my mind outward as I soaked in the water. Each incoming wave carried a cool touch of seawater, mingling with the hot spring rising from the rocks to create a perfectly tempered bath. It was a moment both soothing and strangely familiar, as if stirring some distant memory. If I had to describe it, it felt like being held within the womb of the Earth itself.

Yakushima, a remote island of untouched natural beauty, is home to numerous free-flowing hot springs of exceptional quality. Among them, one stands apart: Hirauchi Kaichū Onsen, treasured by the small coastal community at the island’s southern tip.

More than 400 years ago, villagers discovered hot water seeping from gaps in the seaside rocks. Using chisels, they carved into the stone and arranged rocks to form bathing pools. Since then, it has been cherished as a place of healing for the local community.

There are three baths here, though their shapes can only be seen for about two hours before and after low tide, which occurs twice a day. At all other times, they are submerged beneath the sea. It is, quite literally, an ocean bath.

On this visit, I experienced the place twice: once in the morning at low tide, and again at night as the tide began to rise. During the daytime in peak tourist season, as many as thirty people share the baths in a lively, communal atmosphere—locals, travelers and sometimes visitors from abroad.

At night, however, the number of bathers decreases. Surrounded by nature in its rawest form, you return to yourself. At times you connect with others, at times you reflect inward. This, too, is a treasure of yudō.