Waiting at the kerb with the other obedient pedestrians, I asked a young woman for directions to the Shin-Marunouchi building, one of Tokyo's new breed of urban malls. She pulled out a regular-looking mobile phone, punched in the name and switched to GPS, which displayed a digital map of the area, our location and the destination. Damn, that was good.
But even the Japanese don't yet have mobile software that can map the ever-shifting geography of cool in their capital. So you'll have to imagine the southwesterly drift that has happened in Tokyo over the past decade, as those looking for more sophisticated ways to shop, eat and then shop a little more shifted from Harajuku to Aoyama, on to Shibuya and out to the low-rise hipster district of Naka-Meguro. South of the centre, mega-malls have also sprung up - most notably Midtown, which has its own world-class design museum.
But stemming that westerly tide is a retail revitalisation in the formerly dull financial district of Marunouchi, in the east of central Tokyo. Its name means "within the [castle] walls". A forest of 700ft-high silver office towers, it is bordered by the Imperial Palace's moat, which teems with koi carp, and the immaculate formal gardens - the most green you'll see in Tokyo, not counting the seaweed in your miso.
At first, Marunouchi doesn't appear to offer much in the way of shopping or, indeed, any type of fun. It could be downtown Houston or Canary Wharf. The spine of the district is Naka-dori, a street already home to international fashion brands including Armani, Gaultier and Marni. But try going inside, or even right underneath the apparently joyless skyscrapers to see the future of urban shopping. Spend an afternoon here, staying on for dinner, and you'll find out why it's the city's hottest hangout.
The best place to start is the subway at Tokyo station. Most visitors pass through to board the bullet train, but inside the JR terminus complex is the revamped Daimaru department store, a 14-floor playground inside the North Tower of the Twin Towers complex. It's the place to buy cosmetics: the first floor has 46 different beauty counters.
Daimaru is one of several new retail magnets in the area. Towards Marunouchi's borders with Ginza, to the south, the Marronnier Gate centre is worth visiting for its five-storey haberdashery, Ginza Hands. Browse the expensive chopsticks and Swarovski-crystal studded portable ashtrays. (Tokyo smokers carry their cigarette butts.)
If luxury pangs aren't sated, take afternoon tea in the lobby of the 24-storey Peninsula Hotel, which glows like a lantern at the corner of the palace gardens, at the south edge of Marunouchi. It's as pricey as you'd expect from an establishment that offers guests airport transfers in a Rolls-Royce - but the champagne tea does finish with foie gras lollipops.
The Peninsula's gleaming towers, designed to resemble a lantern, are dwarfed by the twin edifices that dominate the area: the 7,000ft Marunouchi building, constructed in 1923, and Shin-Marunouchi, which opened this winter. While the upper 30 floors of the latter are offices, the lower seven offer fashion and feasting so sophisticated as to make Selfridges look like a pound shop.
It's early evening when I arrive at the base of the Shin-Marunouchi: prime shopping time. The salarymen have just knocked off. Neat professional women are browsing for prepared meals. I follow a stream of them down into the building's basement, the grocery floor. Down here, at dozens of sparkling counters, the gourmet's every caprice is catered for: caramel jam, jewel-like chestnut and green tea sweets, authentic Viennese cafe latte, a "bread bar", selling mini profiteroles for £3 a pop.
Heading upwards, to the triple-height ground-floor lobby, the focus turns to fashion. United Arrows, the excellent Japanese multi-brand clothing shop, has a big branch here. The selection caters to the preppy-minded hipster, a sizeable constituency in Tokyo. Western-sized female hips and male shoulders might preclude the purchase of any garments, but the accessories have one-size-fits-all appeal.
Walking the looping routes around the next three floors - which house fashion, beauty and design stores - is a sexy experience. The lights are low, the marble floors very shiny. This is where young professional couples hang out, halting their promenade only to sit on velvet chaise-longues and hold hands.
The fourth, fifth and sixth floors are a banquet of exclusive restaurants offering yakitori, soba and tempura, along with Italian and French choices. This is not the mediocre "food court" of Western malls; a traditional multi-course kaiseki meal of sashimi, vegetables, seafood and rice can easily cost £60 a head - and that's a casual counter-style place.
The seventh floor is cosiest: called Marunouchi House, it's a small complex of eight bars with a private-club atmosphere. Post-splurge, drink at the Rigoletto Wine and Bar, watching ultra-violent yakuza movies on the big screen. At almost midnight, the retail levels now shuttered, the foodie floors are still peopled by businessmen. This building's motto is "everything for the office worker", suggesting both the rewards and numbing exhaustion of the Japanese work-ethic - but there's plenty of happy shopping for daytrippers, too.
HOW TO GET THERE
Virgin Holidays (0844 557 3861; virginholidays.com) offers five nights' room-only at the Keio Plaza in Japan from £1,039 per person, based on two sharing, including flights with Virgin Atlantic and transfers.
Shop local: the top five
COMME DES GARÃCONS 3-4-1 Marunouchi (00 81 3 3218 152) An outpost of Rei Kawakubo's avant-garde design empire. Smaller budgets will stretch to her purses and perfumes.
MUJI 3-8-3 Marunouchi (00 81 3 5208 8241) The minimal-minded home-ware brand is best experienced on home turf. Stay for a healthy lunch at Meal Muji.
CABANE DE ZUCCA 2-3-2 Marunouchi (zuccone.com) Browse Japanese designer Akira Onozuka's workwear-inspired clothing and collectable watches.
BEAMS HOUSE 2-4-1 Marunouchi (00 81 3 52 208 686; beams.co.jp) The ground floor of the Marunouchi Building belongs to a big branch of this hip home-grown fashion boutique.
CL4LA 1-5-1 Marunouchi (weavetoshi.co.jp) CA4LA, pronounced "ca-shi-la", is the pick of the Japanese millinery stores. Try out the beanies, trilbies and berets.