What will you be wearing, eating, looking at, and living with next? The answers are incubating in Tokyo. Simon Dumenco gets his marching orders inside the most influential city on earth

Just off the tree-lined Omotesando-dori in central Tokyo, there's a boutique called Loveless. It's my third day here, and I'm still finding it difficult to crack the city's aesthetic code. I've been told that this shop is one of the most extravagantly cutting-edge high-end fashion experiences to be had in Tokyo, and yet its storefront is nothing more than a dark brick stairwell whose steeply vaulted ceiling suggests the entrance to a baronial prison or an S&M dungeon.

At the bottom of its grungy stairwell, Loveless opens up into a sparsely lit, rather forbidding windowless space with blackened brick walls. Where am I? Perhaps Hannibal Lecter shops here? Oh, but wait: It turns out I'm on a sort of mezzanine—just ahead of me is the main space, an expansive two-story sales floor lit by a massive twinkling chandelier. To one side is a café and a table laid with Western and Japanese art books. Below me, and accessed by another gloomy stairwell, is a dramatic set piece: an elegant display of one-of-a-kind women's and men's fashions—suits and frocks and five-hundred-dollar T-shirts—bathed in light and punctuated by haloed puddles of halogen spotlighting. Suddenly the S&M dungeon feels more like a black-box theater, its merchandise the stars of some sort of mute Beckett play.

But for all the store's high-minded theatrics and ultra-conceptualized design, what's perhaps most remarkable about Loveless is the fact that the sales clerks are cheerful, solicitous, and entirely game about trying to communicate in snippets of English—which, come to think of it, has been the case in every Tokyo shop (high-end, low-end, and in between) I've visited. For as bewildering, as intimidatingly chic, as Tokyo can be, it's also strangely relaxed and accessible and warm—it never feels off-putting or exclusionary.

As I leave the store, a compact photo book of Japanese interior design in hand, I think, not for the first time, about how unlike any other city Tokyo is, and how magnificently it's defying my vague (and, it turns out, outdated) expectations. In the world's other great cities, fashion of the kind found at Loveless would invariably be on display in some sort of elegant, serene setting meant to evoke an art gallery. But in Tokyo, it strikes me, Loveless's murky, pointedly underground merchandising feels exactly right. Here, if you don't do the totally unexpected, the counterintuitive, you're an also-ran. And so there are hundreds of these offhandedly irreverent basement and street-level boutiques throughout the city, many of them tucked away on obscure side streets and alleyways in unlikely residential settings.

In a sense, that sort of stealth cool is emblematic of the way Japan has been quietly repositioning itself. The Japan that we think we know—a land of nose-to-the-grindstone, grimly conformist, tradition-minded salarymen—is fading, and in its place is emerging a youthful, vivid, often fearless self-expression.