The basement food halls of Tokyo's department stores have become hot places to see and be seen. A writer examines the depachika madness.

Looking for a trendy tempura stall recommended by friends, I descend into the vast, teeming basement food emporium at Takashimaya Times Square, a department store in Tokyo's Shibuya district—and promptly get lost. It's easy to get disoriented by the scale, diversity and sheer gorgeousness of nearly half an acre of the world's choicest comestibles. Dodging a hail of free samples, I thread past a rosy display of German wursts, ranks of yakitori sticks slicked with a burnished caramel glaze, pastel-colored Japanese confections molded into swans and chrysanthemums, and sleek piles of panini at an outpost of Peck, the famous Milanese deli.

Judging from the high-pitched squeals around me, "Oishi!" (delicious!) might be replacing "Kawaiiii!" (cute!) as the battle cry of the Japanese female consumer, a force that pretty much drives the world's second largest economy. Still trying to find my bearings, I scan the shoppers nearby. Two schoolgirls in plaid miniskirts and matching flared leggings perch at a counter in triumph, having scored a bamboo tray of tofu so coveted it's sold only four times a day. Across the aisle, a posse of retro-punk teens in torn fishnets are ogling this week's "it" sandwich, white-bread triangles layered with whipped cream and sliced bananas and kiwis. The sandwich is both kawai and oishi. Beyond them, a prim Ginza matron is deep in contemplation of a $175 pair of muskmelons, no doubt intended as an omiage, or obligation gift.

The food basement at Takashimaya Times Square is one of the dozens of depachika—a contraction of depato (department store) and chika (underground mall)—doing booming business all over Tokyo. To a Westerner these subterranean food halls seem less like places to buy-and-bite and more like mammoth hyperdesigned exhibition spaces devoted to the latest food trends. And it isn't just the profusion (an average food basement stocks some 30,000 items). The thrill of being at a depachika these days is the sense of riding the crest of the Japanese shopping mania, marveling at the virtuoso layering of the ritualistically traditional and the outrageously outré, of handmade and high tech. If Japan is the mecca of global consumerism, depachika are its newest shrines to excess.

Excess, actually, isn't a word one associates with Japan's slumping economy (the mobbed new Louis Vuitton store notwithstanding). But this is where the depachika comes in. In the past, Japanese shoppers would stop at depachika for Belgian chocolates or expensive green tea on their way to the fashion floors. A few years ago, though, with luxury goods sales declining and the general food mania growing—this is a country that airs three-hour TV shows on ramen—stores started adding culinary concessions and features. A Pierre Hermé pastry is infinitely cheaper and just as desirable and status-packed as an Hermès bag. So people came, they spent, the hype grew. Today food basement profits account for more than 15 percent of department store sales.

In their bid to lure customers, rival emporiums outdo each other with endless festivals and promotions (bean-sprout day, bonito-shaving day)—not to mention takeout from famous restaurants and exclusive arrangements with celebrity chefs. Tokyu Food Show in Shibuya stands out for its array of incredible cheeses and rare honeys. The Seibu depachika in Ikebukoro, sprawled out on two floors, awes by sheer size.

To better understand the trend, I take the train back to Shinjuku Station for a guided tour of Takashimaya's food hall. Shinjuku is one of those districts where Tokyo blares at you like some sci-fi movie trailer. In the dim drizzle, the adult-entertainment warren of Kabuki-cho, east of mammoth Shinjuku Station, glows in a jumble of lurid neon. Right by Takashimaya, the new DoCoMo tower rises like a goofy mock-up of the Empire State Building as if rendered for a neo-'60s remake of Godzilla. When the rain starts to come down for real, I look up and note that every single woman on the block has popped open a Fendi umbrella.

Takako Sakata, one of Takashimaya's public relations reps, whisks me downstairs—quickly, quickly. Takashimaya Times Square is one of Japan's largest department stores, she informs me, with 15 retail floors, 28 restaurants and a 2,700-square-foot basement occupied by some 130 concessions, including outlets of local bakeries and international stores like Fauchon. Scattered around are exhibition kitchens where fresh-faced young chefs hand out tastes of fusion potato salad and recipes for truffled croquettes.

Competition for Japanese taste buds, I learn, isn't just fierce, it's brutal: A tenant who fails to impress after a few months is sacked and immediately replaced. Depachika, Sakata explains, are able to change their tenants more quickly than the fashion floors can. In other words, what I'm seeing here represents the cutting (and cutthroat) edge of Japanese taste.

Sakata shows me this week's best-sellers, some of which are literally labeled with flags showing their number-one status. We start at Gramercy New York bakery, a Tokyo version of Manhattan minimalism, where creations bear names like Tribeca and Foggy Mountain. "These are more sculptural than French cakes, and more of a novelty," Sakata says, pointing to a confection adorned with a jagged praline rendition of the Manhattan skyline. Also huge at the moment are smoked-salmon onigiri (rice balls), plain-looking egg-salad sandwiches (go figure) and a dark-and-milk-chocolate mousse from Parisian pastry legend Gérard Mulot. Besides pastries, one of the best-selling categories is sozai, deli-style foods that range from fettuccine con salmone to Kobe-beef patties that taste richer than foie gras.

The stampede around China Tea House with its 200 types of tea indicates that oolong is the leaf of the moment. Though for all I know tomorrow will bring a frenzy for chile-spiked Mexican cocoa. Or salt. Sakata hurries me now to a shelf displaying 70 kinds, from fleur de sel de Guérande to boutique Okinawan brands. Saline advisors stand by, ready to suggest which salt would work best with which dish.

But how and why do particular items become popular, I ask Sakata. Her shrug indicates that food-hall trends are as difficult to predict as which stiletto will achieve cult status among fashionistas. But when it happens—bam!—the counter is swarming with media. And once paella hand rolls or sweet Nagoya custards or German Roggenbrot are featured on TV and in weekly magazines, the queues can last hours. The most desirable items are rationed like Birkin bags. Fueling this food mania, daily newspapers regularly print a list of current depachika best-sellers, while women's magazines devote as much space to sozai trends as they do to hem lengths. Food-basement junkies keep abreast of the novelties and promotions by logging on to

Many customers tell me that the depachika craze reflects the changing reality and the new-found independence (or selfishness, some argue) of the Japanese working woman. Why cook a meal from scratch in cramped living quarters after traveling an hour on a jam-packed train? Why not hang out at an underground food theme park gawking and grazing, then carry out an Italian salad or an Osaka seasonal delicacy for the family?

Among the most influential trendsetters are the "OL," or office ladies, in their twenties and thirties. Some are married with kids; some are "parasite singles," a Japanese-coined term for people who live with (and off) their parents and spend all their disposable yen on luxury goods. I strike up a chat with such a woman, Hiromi. Her bob is à la mode auburn. She's fond of Piedmontese cheese, green tea pound cake and furry pink stoles. She can mix checks and polka dots with aplomb and giggles when I ask if she prefers French or Japanese pastries.

"By now we Japanese don't distinguish between Western and domestic," she declares. "Udon or pasta—it just depends on my mood."

Hiromi can't afford to eat out every night like she used to. But she'll never give up "prestige foods" or debase herself by shopping at a konbini (convenience store). She first started coming to depachika to pick up a bento box, but now she's addicted, dropping by every night after work on her way to the train just to keep up with what's new. Someone could probably get very rich, it occurs to me, by starting a Depachika-holics Anonymous.

By the time I finally find that trendy tempura counter, it's lunchtime, and the line snakes all the way past the Chinese dumpling stall. To make matters worse, on my way out I suffer a head-on collision with a depachika baba, one of those tiny oba-san (older ladies) who propel themselves into action the second a vendor announces a sale. What this particular oba-san is planning to do with two dozen red bean—filled scones is anyone's guess. I go out into the rain, consoling myself with the thought that in the time it took for the elevator to whisk me upstairs, tempura has probably already become passé.

Anya von Bremzen is the author, with John Welchman, of Please to the Table: The Russian Cookbook and of Terrific Pacific Cookbook.