Inside a pitch-black 1930s Milanese theatre, visitors walked around an empty space filled with ambient sounds, light fog and mirrored walls.

These elements lent a haunting aura to the halls of the once-derelict Cinema Arti in the San Babila district and were part of an installation commissioned by London-based fashion label Cos to launch its spring/summer 2016 collection at last month's Milan Design Week.

But rather than use models wearing its designs, the brand opted for something more conceptual - a series of pulsating spotlights that shone on whoever stepped under it.

Mr Martin Andersson, 39, head of menswear design at Cos, says: "Installations are how Cos tells a story to our customers about what our brand aesthetic is - that is so simple yet surprising in its approach.

"We thought that using just light as an interactive element was really interesting because it's so basic, yet it instantly transforms the space into something different. It's showing Cos in a different media, instead of using clothes."

To achieve this, the brand looked to the one person whom it felt could best capture what it wanted to achieve - Japanese architect Sou Fujimoto, one of the fraternity's rising stars.

The Forest Of Light, as the installation was called, is typical of many of his works in that it evolved from the concept of a forest.

Fujimoto, 44, explains his forest obsession: "Architecture is like a forest - a place of diversity, where living things in it move freely and there are different functions. And just like a forest, it's an exciting challenge to integrate all the things an architecture piece needs."

Using something intangible such as light as his main material is a bold move, and indeed the University of Tokyo architecture graduate's body of work is anything but safe.

From the grid-like "floating cloud" pavilion in a park for London's Serpentine Gallery (2013) to stacking houses as part of a housing collective in Tokyo (2010), Fujimoto has made a name for himself doing the unconventional.

It was what drew Cos' head of womenswear design Karin Gustafsson and Mr Andersson to approach him. This is the brand's fifth participation in Milan Design Week. It had worked with big names such as New York studio Snarkitecture and Japanese design studio nendo.

Mr Andersson says: "For these installations, we always pick people whom we admire, or from whom at times we draw inspiration for our collection from their work. With Sou, we're huge fans.

"We experienced his Serpentine Gallery Pavilion in person and it was amazing to see his attention to detail and how the pavilion was never the same through the day - it was constantly changing with the light. That was smart architecture."

It is not just Cos who is singing his praises. In the last couple of years, Fujimoto has been gaining recognition for his work.

One of his biggest accolades to date: winning in the architecture category at the 2014 Innovator Awards given out by The Wall Street Journal's award-winning WSJ. Magazine. Winners for the Innovator Awards range across industries from entertainment to technology and are chosen by editors of the magazine. Other big architecture winners include British architect David Adjaye.

Fujimoto says his unusual, boundary-pushing work is his way of starting a conversation about how architecture of the future can be better.

He points to houses as people know them today. When they were first built, people thought the structures looked like "factories or a garage" because of their boxy shape.

"We think that look is normal today. But that's boring and maybe not relevant anymore. People's lives are constantly changing, so we should build something that suits the way they live now," says Fujimoto, who designed a bus stop in an Austrian village out of tall, thin steel rods.

Open to the elements, it has a winding staircase between the rods where those waiting for the bus could head up and park themselves on the bench.

Despite his quirky work, Fujimoto in person is cool and relaxed, much like the average Joe.

He chuckles when you suggest he might have a "crazy streak" when it comes to architecture and says his ideas come from the routine of life. He runs his 40-strong Tokyo-based studio Sou Fujimoto Architects and spends a large part of his day in meetings, consulting with his team and talking to clients.

Fujimoto, who is married and has a one-year-old son, says: "Every brilliant and crazy idea comes from boring research and case studies. It's not like a genius makes a discovery from nothing. It's repetition of daily life that gets him there."

Given his achievements, he appears on track to be the face of the next generation of Japanese architects. But it is not something he strives towards. Nor does he feel the pressure to win a Pritzker Architecture Prize - the industry's most prestigious award - in the footsteps of Japanese architects Tadao Ando and Toyo Ito, whom Fujimoto counts as a personal mentor.

He says: "I'm not thinking so much about how I have to keep the legacy (of Japanese architects) going. I'm doing what I think is good. Those in the future can decide if I'm good or bad. The one thing I can do now is to make good architecture."

• The writer's trip was sponsored by Cos.

MILESTONES

1971: Sou Fujimoto was born on the northern Japanese island of Hokkaido on Aug 4 1994: Graduated with a degree in architecture from the University of Tokyo

2000: Established Sou Fujimoto Architects in Tokyo. The office is in the Shinjuku area

2001: Started as an adjunct lecturer at the Tokyo University of Science. Fujimoto would later teach at Showa Women's University and Kyoto University, among other educational institutions

2008: Final Wooden House, a wooden bungalow made of stacked lumber beams, won in the Private House category at the World Architecture Festival. A year later, Wallpaper* Design Awards crown the project - in the Kamamura village in the south of Kyushu - the Best New Private House

2013: Designed the Serpentine Gallery Pavilion in London. At 41, he was the youngest architect chosen to design the temporary installation

2014: Received The Wall Street Journal Architecture Innovator Award 2016: Presented his installation, Forest Of Light - a commission by London-based fashion brand Cos - at Milan Design Week