German-born, Tokyo-based architect Florian Busch says that witnessing a building rise from an open plot of land is like watching a plant grow.

"You watch as every leaf sprouts," he says. "Architecture takes such a long time, but the satisfaction when you see something at the end is amazing."

Recently, Busch's attention has been focused on a three-story house that is gradually taking shape on a tight plot of land in Tokyo's Takadanobaba district, and the thrill has been particularly special. When it is finished, later this month, it will be the first building the 38-year-old has completed since establishing his own office, Florian Busch Architects, here in Tokyo.

There are very few non-Japanese architects who have chosen to launch their careers in Japan — to practice here you need a locally issued license, or to hire someone who has one. Perhaps the most prominent Japan-based foreign architects are Briton Mark Dytham and Italian-born Astrid Klein, who set up Klein Dytham Architecture together in 1991 after working for two years at the office of well-known architect Toyo Ito.

Busch also worked with Ito — for almost five years between 2004 and 2008 — and he laughed when asked whether Ito was particularly open to foreign staff.

"I think there are architectural offices with the same openness toward foreigners," Busch starts. "But Ito now has a big advantage — the exposure abroad. He really has a constant need of people who can speak the language overseas and also understand the cultural aspects."

Busch's work in that role at Ito's office, which is best known for buildings such as the Sendai Mediatheque in Miyagi Prefecture and the Tod's building on Omotesando in Tokyo, lasted for longer than is the case with most foreign staff. Before he started working for Ito he had already traveled to Japan twice — in 1995 and 1997-'98 for research — and he had also married a New York-born Japanese woman, and was able to speak the language.

"The first work I did at Ito's office was a proposal for the Ghent Forum for Music, Dance and Visual Culture in Belgium," he says.

The firm ended up not getting that job, but Busch gained something important from the experience nevertheless.

"I remember just after we lost that competition, Ito and I walked to the site together," he says. "I was so frustrated, because it was obvious we should have won, and Ito said, 'Ten or 15 years ago, I would have been very mad, too.' "

Busch came to respect what he saw as the 70-year-old's "mental maturity" for other reasons, too.

"Ito has a huge capacity to turn ever-occurring constraints and crazy requirements by the clients into positive assets," Busch explains. "Not many architects are like that. Usually, they compromise and do whatever the client says, or they say 'I'm out of here, we're going to build it my way or no way.'

"Maybe it's actually good that the client tells you one week before construction that their budget is in fact not as big as they thought. Or maybe it's good that they suddenly say they don't want orange, they want green," Busch says.

The young architect has adopted that approach for the new Takadanobaba residence, where the key constraint lay not in the budget or the color request, but in the nature of the site itself.

A long, narrow plot measuring about 5 meters across and 22 meters deep, it is also surrounded on three sides by three- and four-story buildings, all built to about 50 centimeters from the boundary.

"The usual approach by a Japanese builder would be to put a small house at the back of the plot and then fill the front with parking spaces for cars," he says. "Of course, that was out of the question."

"The key issue was how to get natural light in," he continues, before grabbing a piece of paper and folding it so that its cross section resembled turrets across the top of a castle wall.

"This became the key concept of the design," he says.

Standing the folded paper up vertically, he shows how the floor on the first floor bends up to form a wall, and then that folds at 90 degrees to form the floor of the second floor, and then that bends up to form a second floor wall and so on.

Busch's design meant that on each floor just one of four walls would be made of concrete. The rest, he said, would be glass.

"This house has a greater area of glass walls than it does total floor space. That's unheard of," he says.

In this way, the constraint of a narrow, poorly lit site was turned into an advantage and dictated the entire concept of a unique design.

Walking through the site last week — just prior to the installation of the glass walls — Busch explained how even on the bottom floor, the long glass walls brought in natural light.

Once the main concept was determined — and the support of the client, a young couple, attained — the task became one of realizing it as true to the vision as possible. And once again, Ito's approach of balancing commitment to the overall vision with a willingness to make creative compromises came in handy.

In order to convey the impression that the house consists of a single, folded slab of concrete, a series of thin solid-steel pillars had to be developed in order to hold up the side of each floor where there was no concrete. This required precise calculations of the minimum amount of steel that could support the building (just six pillars on the first floor, five on the second and four on the third) and the services of a specialist steelmaker.

More problematic were the frames for the vast walls of double-glazed glass that would enclose each floor.

"We had so much trouble with the glass," Busch explains. "I initially wanted wooden frames, but that proved difficult in terms of getting (local government) approval."

Busch finally settled on steel frames, which could be made thinner than aluminum ones. The problem was that in order to use the more unusual steel frames in combination with transparent glass, Busch and his staff would have to get approval themselves — a process that would have taken about three years.

To circumvent this problem, he ended up using wire-reinforced glass — the fire regulations for which were less stringent.

"It's frustrating, but I think I was right to stick with the narrow steel frames," he says.

To further emphasize the building's folded-concrete concept, Busch avoided making any internal walls.

"We will use curtains, instead," he says. "We're working with a fabric designer to interpret the Japanese idea of layering spaces like with fusuma and shōji with textiles."

Busch says the decision to establish his own office in Tokyo stemmed from an understanding with Ito that he would eventually break out on his own and also the fact that he had three clients he could take with him.

"I initially had told my wife that we'd be in Tokyo for just two or three years," Busch explains. "But after five years with Ito, I had established so many contacts with engineers and so on here. I would have been starting from scratch in London."

The young architect says it took a while for his office to get "traction" in Tokyo — with the global financial crisis striking just months after Florian Busch Architects launched — but now things have settled.

He was chosen as the "show designer" for the annual design-trade fair, Tokyo Designers Week, which was held last month in the capital, and he is now also making regular trips down to Shimoda in Shizuoka Prefecture, Hokkaido and Chiba Prefecture, where other residential projects are in various stages of development — some in what might be called "seed" state, and others sprouting into "plants."