Sunset birdsong reached fever pitch as I stepped out of my clothes. With only a row of orange-leaved trees for protection, I gingerly stuck a toe into the pool of steaming water.
The Niki Club, a retreat set among the dense green mountains of northern Honshu, aims to reconnect city dwellers with nature. And so I should have been prepared to find myself standing naked in a forest at dusk before taking a dip in a natural hot spring or "onsen". Fortunately, my urban conservatism proved unnecessary as it is rare to encounter any other people while exploring the hotel's 14 hectares of woodland, streams, meadows and rice fields.
The hotel itself is a celebration of modern design in a bucolic setting. Scattered among the trees are a series of concrete, wood and glass guestrooms linked by overgrown paths, bridges and steps. Four Japanese architects created the original buildings 21 years ago, while Terence Conran designed the recently opened East Annex - a tranquil network of wood-clad guesthouses, a restaurant and spa.
The library is perfect for pre-dinner drinks - with its striking long, low bar in orange cherry blossom wood, an open fire and grand piano playing in the background. La Brise restaurant is a formal affair with five-metre-high polished concrete wall, bold abstract canvases and a creative menu. Less formal but equally stylish, is the East Annex restaurant created by Conran.
For those in need of pampering, a serene, light-filled spa offers a series of massage treatments based on the hotel's signature blended aromatherapy oils. But the focus lies on outdoor life. There is cycling, fishing and rambling while watercolour palettes are available at reception for inspired artists.
And those who feel uncomfortable at the prospect of al fresco onsen-dipping, rest assured: there are also two indoor onsen baths with picturesque views of the woodland.
Niki Club, 2301 Takaku Otsu Michishita. Nasu-machi. Nasu-gun Tochigi-ken 325-0303, Japan (00 81 287 78 2215; www.nikiclub.jp). Home to the Imperial Family's summer retreat, Nasu feels a million miles from the bustle of the capital. The hotel is set on the edge of Nikko National Park and is surrounded by mountainous forests and farmland.
Time from international airport: Nasu is one hour from Tokyo by bullet train, costing around ¥10,900 (£45) return. A free pick-up service three times a day takes guests on a 30-minute drive to the hotel.
Clean lines, natural materials and large windows feature throughout the 42 rooms, none of which seem to have dated. The original guest rooms are glass-fronted hillside cubes facing a river. Six further rooms overlooking a pebbled pond have tatami mat floors and futons in traditional Japanese style. The new Conran rooms have double-height ceilings, towering windows, a mezzanine for sleeping and iconic design gems such as moss green Fritz Hansen swan chairs.
Freebies: Small bottles of Marks & Web aromatherapy products. Soft black shawls, white tracksuits, silk pyjamas and long puffa-style coats are also available to wear while staying.
Keeping in touch: Presumably because the idea is to lose touch, internet access is limited to a small number of guestrooms and the lobby in the East Annex.
THE BOTTOM LINE
Doubles from ¥52,900 (£225) including breakfast. Book via Design Hotels (00800 37 46 83 57; www.designhotels.com). I'm not paying that: Head to the Rindoko Royal Hotel in Nasu-Kogen (00 81 287 761 122; www.daiwaresort.co.jp) which has doubles from ¥41,300 (£183) including breakfast.Reuse content