Hell or hot water

Of all the ancient customs specific to Japan, the onsen is probably the easiest for a foreigner to join in. There are rituals involved but they are rudimentary: strip buck-naked, scour yourself clean and lower yourself into an indoor or outdoor bath of hot natural spring water.

Given that every part of this process is conducted in full view of vastly more experienced native bathers, whose language you do not speak and whose flesh does not turn a piggy tint of pink on contact with near-boiling volcanic liquid, many visitors might still prefer to try seppuku instead - the more archaic but slightly less mortifying art of suicide by self-disembowelment.

There are onsens almost everywhere in Japan, ranging from busy, splashy neighbourhood bathhouses (known as "sento", which tend to use common tap water), to high-end resort complexes in the mountains, built on steam that's been bursting from the ground since these islands first rose out of the ocean. Yudanaka, north-east of Nagano, is one of many alpine spa towns but is particularly well-known for its snow monkeys, which spend most of the winter sitting neck-deep in a specially constructed onsen of their own, with their livid, puce-coloured faces suggesting roughly the same stupefied contentment that a human might feel. Most of us, however, can only aspire to a snow monkey's lack of self-consciousness.

I feel confident enough at the Yudanaka Seifuso hotel but only while I'm wearing my yukata, a patterned cotton robe that lets me stride freely and proudly down the corridors like a samurai just chillin' after battle. The establishment itself is a typical, traditional wooden inn founded in the mid-19th century, when the original owner dug down more than 45 metres to tap into his own spring. It has since been appended with a maze of concrete annexes and divided into several different private and communal baths, with separate hours of use for male and female guests.

Tonight, there are two other gents partaking of the evening session in the open-air "rotenburo", a stone tub set into a liquid courtyard, fringed with rocks and plants. These men rightly presume that I've never done this before, directing me towards the outer washroom and miming the procedure - sit beneath the shower on a plastic bucket and scrub vigorously from head to toe.

No traces of dirt or soap are permitted in the bath itself. No tattoos either, in a measure that was originally supposed to keep out members of the yakuza (Japanese mafia) but also obliges Westerners to wrap their ink in bandages. Finally, I am ready to get in. And if my right foot is an accurate temperature gauge, then the water seems on first contact no more or less hospitable than a lake of magma at the core of the planet.

The old boys sitting quietly in the onsen are not quite polite enough to refrain from laughing at my girlish shrieks, even if they don't know the literal meaning of the various swear words I'm compelled to use. But the younger of the two speaks English well enough to inform me that the men here prefer to repeat the word "atsui", which simply means "hot", until they can acclimatise.