I’ve been in Japan three days by the time I arrive at HOSHINOYA Tokyo and I’m already wrestling with difficult questions I hadn’t foreseen. How can a metropolitan area holding 37 million people have absolutely no litter? What happens in an owl café? How is everyone so good at sleeping on public transport? What is a Pocari and why does its sweat taste so good? The custodian of a ninja-themed maid café tried to entice me inside at 11.30am on a Tuesday by shouting to me “do you like ninja?” … well, do I like ninja?! (No – I was scared).

But for this hotel experience I’m trading the teen culture of Harajuku and the manga madness of Akibahara for the uptown chic of HOSHINOYA, an 84-room sanctuary right in the heart of Otemachi, Tokyo’s financial district. The hotel is a sleek black tower wrapped in metallic komon patterns: architect Rie Azuma styled the 17-story building to resemble a jewellery box tucked between the corporate towers crowded around it.

HOSHINOYA is an urban ryokan – something of a paradox. Ryokans are traditional Japanese inns, floored in tatami mats and centred around natural hot springs, where weary travellers can recuperate, usually while enjoying Japan’s breathtaking scenery. It might not be mountaineous but Japan’s salarymen-swamped financial district is a sight to behold, and a ryokan experience is certainly welcome.

On arrival, our shoes are off immediately, sequestered in a wooden locker where they’ll remain until we venture outside, guarded by the kind of polite gatekeepers of etiquette that rule Japan with an iron fist in a velvet glove. We’re swept up ten floors to our room, codename Kiku– a corner suite so quiet and peaceful it’s easy to forget there are any other guests at all, never mind tens of millions of people outside.

The room has a large low seating area in front of a TV hidden by mirrored magic – because who wants to see gaudy screens in a ryokan? – and a sturdy table that will be important when the 15-part symphony that is breakfast arrives. The bed is huge, floor-level, and flanked by sliding white screens that reveal the komonpatterns outside, creating shifting shapes and shadows in the morning light.

Cruise through the walk-in wardrobe and you’re headed to the bathroom where a deep, square tub sits, roughly sizeable enough for a football team (of course, there’s a shower if you’re pushed for time). Open the final remaining door and a light comes on and a toilet lid swings up, because this is Japan, where Toto has won and a toilet seat will never be cold again.

The trump card of HOSHINOYA Tokyo, the gorgeous room and shared lounges aside, is situated on the 17thfloor. Getting natural hot spring water up 1500 feet from deep underground to the top of a skyscraper is no mean feat, but it wouldn’t be a ryokan without it. The Mrs and I step out of the lift and separate – onsenare gender-segregated, what with the nudity – and transition first into robes, and then into not very much at all. After a quick rinse I’m lavishing in curative, piping-hot water, staring up at the black sky through open roof. The baths are open through the night and a couple of other guests are availing themselves; we sit in silence, the buzz outside barely audible, letting jetlag and fatigue slip away.

One of the hotel’s other killer features is its restaurant, in the basement 18 floors beneath the hot springs. Here they are hiding a French-trained executive chef, Noriyuki Hamada, who takes us through a 9-course wine-paired tasting menu heavy on fish and rich in quality. The restaurant space itself is minimal, with a small number of covers separated by sliding screens and large, sparse tables ready to house multiple dishes and wines.

Before the courses even arrive, a black cracker composed of bamboo charcoal, fish and peppercorn, accompanied by a string crisp fillet of fish in seaweed, has us scratching our heads at the sheer craftsmanship of it all. The signature ‘five flavours of delight’ is an entire meal in miniature, running from starter through soup, fish, main course and dessert, in the form of five hand-crafted suspended mouthfuls balanced on stones, ranging from mushroom soup to pumpkin pie.

Seafood is lovingly showcased and greedily consumed, ranging from horse mackerel and conger eel through to soft-shell turtle and rough-skin sole. Painstakingly chosen wines and sakes complement each course; by the time we get to the dessert the general euphoria is peaking. The dessert tips me over the edge – roasted tea leaves, chestnut, cream, brittle sugar and meringue wrap around a bitter sauce.

We step back a few courses to finish with a particularly fine Galician red and head back upstairs, stuffed, to unwind at the hot springs. When breakfast rolls around, it’s an exercise in indulgent precision: a jigsaw of boxed delights, assembled lovingly on the table in our room. Nothing kicks off your day better than pickled vegetables, raw fish and rice porridge, but we try both western and traditional breakfast options: both well worth the wait.

HOSHINOYA has more in store for guests ready to try new things; at a tea ceremony on tatami mats, in front of a floor-recessed kettle, we learn how to make and serve our own tea. Each evening traditional Gagaku performers play music and perform while guests try different types of sake – the unfiltered, milky-white variety was other-worldy.

The staff have a wealth of knowledge about the immediate area and wider Tokyo too, if it’s restaurant reservations or shops in Ginza you’re looking for. But once the shoes are off, the doors slide shut, and the hot water is running, you’ll find it hard to leave. Putting shoes on is a whole to-do. And with this sort of experience on offer, why would you want to?

Tom was hosted by HOSHINOYA Tokyo, the city’s first luxury traditional ryokan inn. Set in a 17-storey skyscraper in the prestigious Otemachi district, the property combines contemporary design, traditional craftsmanship and high-tech touches. The restaurant is renowned for developing a new culinary style, Nippon Cuisine, which fuses French techniques and Japanese ingredients. As well as spa treatments, guests can also take part in various experiences offered by the hotel including a Japanese tea ceremony, kodo (the art of appreciating incense developed from an ancient parlour game), and Japanese Sake and wine tasting with Grand Kagura (Japanese acrobatics performance). The top floor is home to an impressive open-air onsen (natural hot-spring bath) and a spa offering Japanese-inspired treatments. Activities include An overnight stay costs from £498 per room per night (two sharing; room only). For more information, visit www.hoshinoya.com.