Sou Fujimoto’s career may have gotten off to a slow start, but these days he is a hard guy to catch. With multiple projects in Japan and commissioned work around the globe, the architect’s practice has moved into high gear. And it doesn’t show any signs of losing speed. During a recent pit stop at his Tokyo office, Fujimoto took time out to talk about his career and where it is headed.

When not on an airplane, Fujimoto presides over his 30-person firm, occupying the top floor of an old printing company in central Tokyo. An airy, loftlike studio, it holds a maze of desks, punctuated with large study models. Though he has a private office, Fujimoto rarely uses it. Instead he prefers a large rectangular conference table, out in the open, where he can engage easily with his staff. When he really has to concentrate, however, Fujimoto sometimes heads off to Starbucks, a deeply ingrained habit that predates the launch of his practice in 2000.

Before he established his office, coffee shops were Fujimoto’s refuge from his one-room combined living and working space. After receiving his undergraduate degree from the University of Tokyo, Fujimoto neither entered graduate school nor apprenticed himself at an established firm. “Basically, I was afraid of everything,” says the architect shyly. “I was afraid to show my portfolio, but I was also afraid of being overly influenced [by a mentor].” Instead, Fujimoto settled into a comfortable pattern of reading, sketching, and entering competitions on his own.

Unsurprisingly, this relaxed, unorthodox approach to professional development did not sit well with Fujimoto’s parents, living up on the northern island of Hokkaido. Eager to jump-start his son’s career, Fujimoto’s father, a psychiatrist, commissioned the designer to create a new wing for his hospital. “That’s when I realized that I didn’t know anything practical about architectural design,” notes Fujimoto, smiling.

This period of professional groping came to an end a few years later, when Fujimoto got another commission in Hokkaido—this time for a residential facility for kids, run by his father’s colleague. A cluster of white cubes bound by window walls, the Children’s Center for Psychiatric Rehabilitation caught the attention of the media, and, from then on, Fujimoto was off and running. Urban in concept, the striking building is a refreshing and dynamic play on scale.

Today Fujimoto remains entranced by the relationship between architecture and urbanism—an interest brought out by living in Tokyo, where narrow, winding paths packed with small two-story structures abound. Functioning as communal backyards where kids play and neighbors gossip, these passageways are open to the public but also extensions of the adjacent houses. “I was fascinated by that condition,” explains Fujimoto. “I thought it would be nice to make a city like architecture or architecture like a city.”

Like many architects, Fujimoto tests out new ideas by designing homes. Small and quick to build, houses are perfect laboratories for experimentation—especially in Japan. Here most domiciles last only 30 years before being torn down; few people want to buy old houses, so the residential resale market is practically nonexistent. One of Fujimoto’s first opportunities to blend building and city came from his in-laws, a retired couple ready to replace their outmoded house in Oita City. The resulting home, House N, is a bold set of stark white nesting boxes that continue their city’s concentric organization: a web of pedestrian pathways inside a network of streets within a grid of multilane roads. Well-orchestrated openings in the house boxes admit light, views, and air, enough to sustain even the leafy trees growing in the covered terrace without compromising the clients’ privacy.

By contrast, Fujimoto’s Tokyo Apartment project has a strong urban character but is all “house.” His answer to collective living, the building consists of six discrete house-shaped components, linked by external stairs and containing four apartments. Pure white and jumbled on top of one another, they echo the crowding and chaos of Tokyo that Fujimoto adores. While living in Tokyo stimulates Fujimoto’s curiosity about the play between scales, his interest in this idea is not limited to Japan. His museum on a grassy hillside near Aix-en-Provence is speeding ahead. Composed of ten freestanding, three-cubic-meter boxes—each one earmarked for a single artwork—it is barely a building. “We call it the Smallest/Largest Art Museum,” laughs Fujimoto. If he has his way, Fujimoto hopes to test-drive smaller-scale projects, like designing furniture. Peering out thoughtfully from behind his oval-framed glasses, the architect explains, “It is not necessary to divide the city and architecture or architecture and furniture. By melding them together, we can create something entirely new.”