Katayama has a dozen or so interiors to his credit in Harajuku-Aoyama, Tokyo's fashion and design district. All within walking distance of one another, they are boutiques that, in almost every case, aggressively cater to a youthful clientele for whom shopping is an adored cultural pursuit. ''You're not just buying the product,'' Katayama says. ''You're also buying the time you spend.'' [...]

Now 36, Masamichi Katayama studied interior design in Osaka, although he is quick to point out that it was strictly technical training, with no theoretical or academic courses. ''I learned the philosophy of what I do by shopping,'' he says. ''I'm a consumer first and foremost. Life isn't fun 24 hours a day, so shopping should be.'' He lights cigarette after cigarette as he speaks, taking no more than three drags on each before moving on to the next. [...]