Japan’s famed hot springs, or onsen, are full of invisible tripwires, from nudity to tattoos. A certified onsen sommelier shares advice on how to best enjoy the experience.

It’s 5am and I’m naked on a mountainside. Night still holds sway over the sky, the air is thick with steam, and a single bead of sweat runs slowly down the back of my neck. The onsen (hot spring) I’m ...

I wrapped my yukata, a cloth kimono, around my naked body, pulling the left side of the fabric over the right, as instructed, and tied the obi sash securely at my waist. The hotel provided these robes ...

TSUCHIYU ONSEN, Japan — For 1,400 years, travelers have come to this town in the foothills of the Azuma Mountains, on the outskirts of Fukushima City, to bathe in the famed healing waters of its hot ...

For decades, new plants have been blocked by powerful local interests, the owners of hot spring resorts, that say the sites threaten a centuries-old tradition. Credit... Supported by By Hiroko Tabuchi ...