1. Shoes come off at the entrance and are placed in a locker. In separate changing rooms you place everything else in another locker. You receive one big and one small towel. The small towel is used to cover your modesty (or small tattoos). This should go nowhere near the bath water. Place it elegantly on your head.

2. Bathe before you enter. Bathing stools for sitting and washing line the entrance to the baths. Thoroughly scrub every centimetre of skin and rinse off all soap before entering the bath. An embarrassing soap-slick emitting from your body is not ideal.

3. No tattoos, please. Sad but true; ink is out because of the Yakuza association. You could try a waterproof plaster … or stay in a ryokan with a private onsen.

1. Hoshinoya Tokyo

Hoshinoya Tokyo is a modern answer to the traditional Japanese inn or ryokan. Its rooftop onsen is open to staying guests, and offers a sublime design and relaxing mineral waters pumped from far beneath the bustling Tokyo roads. A large funnel frames the kaleidoscopic sky in the outdoor bath, while the sun or moon cast artistic shadows: the perfect Zen template for a naked mind.

Before you enter the onsen waters; everything your eyes fall on, crafted by architect Rie Azuma, is a full-immersion experience into Edo hospitality and the artistic heart of Japan. Floors, shoji screens, wood slat front doors rooms are all part of the experience. Guests are encouraged to wear designer yukata-kimonos provided for the duration.

Dining at Hoshinoya is traditional omakase style. There is no bar but from 5-7pm you can enjoy free sake tasting while traditional Edo performers entertain you. Also recommended is the morning Japanese tea ceremony experience.

2. Yu, the Spa by L’Occitane at Hotel Chinzanso

Yu, the Spa is set in a huge Japanese botanical gardens that, throughout the year, create a theatre of seasons. The haiku poet, Basho, lived in a house overlooking it. Historically important buildings include a shrine, a temple and a thousand-year-old three-story pagoda from Hiroshima, built without using a single nail.

All there is left to do to feel completely naked is to bathe in the onsen waters brought from the hot spring region of Ito in Shizuoka Prefecture famous for healing and detoxification. The spa has luxury massage and facial treatments. You’ll find a variety of restaurants in the luxury Chinzanso hotel and traditional houses in the gardens.

3. Oedo-Onsen Monogatari, Odaiba Tokyo Bay

More than an onsen, this is a historical theme park combining tradition and fun. Visitors don cotton yukatas, in the colour of their choice, and enter the vibrant life and times of an Edo-era village. You find inside baths, outdoor baths, hot stone saunas and steam rooms. There are hungry feet-eating fish, massage spas (and chairs) and fortune telling.

The natural hot spring water is pumped from 1,400m below. The restaurants use a barcode on your locker key so that everything can be paid on departure. A full fun day experience and overnight accommodation is also available.

4. Saya No Yu

Built in an old Japanese house with a traditional Zen garden, this is a good alternative day trip for anyone worn out by the hustle of Tokyo. The atmosphere is relaxed, with indoor and outdoor hot springs pumped from 1,500m beneath the surface.

There are 14 types of baths, a ganbanyoku hot stone bed, dry and steam saunas and a peaceful restaurant with views over the gorgeous garden.

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