Kengo Kuma is one of Japan's most acclaimed modern architects. Curiously, however, he dislikes much of the country's modern architecture, including perhaps its most imperious and striking example - the Tokyo Metropolitan Government Building, which looms over Shinjuku. 'Japanese architects have lost their courage,' he laments. 'It's a symbol of their loss of confidence in society and in the future.' Meanwhile, China, where he is much in demand, is casting aside its unique architectural inheritance in the rush to modernise, says 56-year-old Kuma. He argues that Japan, which absorbed many of the ancient Middle Kingdom's design traditions, can help China recover the best of its past. Having completed about 60 construction projects, the soft-spoken architect believes that profit should take a back seat to quality. Kuma is increasingly drawn to smaller, modest commissions that use natural materials that meld with - rather than impose themselves on - the environment. 'I don't want to express myself in nature, I want to listen to it,' he explains in his office in Tokyo's Aoyama district. 'The construction site gives a big hint about what to do, if you can hear it.' Yet he is probably best known in China for the huge, upscale Sanlitun Soho development, which opened this year in his favourite city, Beijing. Despite its mammoth 466,000-square-metre scale, however, he says the finished product is faithful to his design obsessions - to soften hard urban lines and incorporate, rather than ignore, local contexts. An open development with no walls and the neighbourly feel of its New York namesake, one of the Sanlitun Soho's most striking features is what he calls the 'Grand Canyon effect' achieved by the water pathway that runs through the length of the complex. Born in the port city of Yokohama, Kuma has two distinct eras to his career. During Japan's bubble economy, when inflated land and building prices encouraged architectural egos to run riot, he was a disciple of what he calls the architecture of fragmentation - his monumental, imposing buildings would intrude into the Tokyo landscape, and 'dissolve and blend into the chaos that surrounded them'. But the collapse of the bubble after 1990 sparked a profound creative change. 'I got a chance to work outside of Tokyo, in small villages,' he recalls. There he began to explore how to ease his buildings into the local environment and harmonise them with local practices and culture, using the materials he found around him. In projects like the stunning cedar-wood Yusuhara Town Hall (1994), in the southern Kochi prefecture, he rediscovered and refined the pre-modern Japanese traditions of design, carpentry and the use of space to make his structures light and airless - a minimalist process he calls 'erasing architecture'. That period was about rediscovering his architectural soul, he believes. 'What I learned at university was how to build big concrete buildings. I wanted to go beyond modern architecture. It was very frustrating because I couldn't find a way to realise my sensitivities, until I went to the countryside.' He compares this approach to one of the giants of 20th century design, Le Corbusier, whose robust concrete buildings 'waged an all-out war on nature'. The architectural contrast, Kuma says, was the source of Le Corbusier's beauty, but he strove for the 'exact opposite'. So began his quest to recover the traditions of Japanese architecture. 'I found that the workers in the countryside still loved their materials - cedar wood, rice paper, the soil - and they were very slow,' he says, smiling at the memory. 'The process was very different from how things were done in Tokyo and I learned a lot.' Kuma stressed that he didn't - and couldn't - abandon concrete in one of the most seismically unstable countries on the planet. But in key post-bubble works like the Hiroshige Museum (2000) in rural Tochigi prefecture, built to house the work of artist Ando Hiroshige, there is a new and deep sensitivity to place and context: the concrete is embedded deep in the structure, which uses local cedar, rice paper and glass. And its rectangular shape is designed to maximise views of the local countryside, appropriate to an artist whose work heavily depicted nature. Those concerns are evident in Kuma's first major Chinese project, the Great (Bamboo) Wall (2002), one of a series of houses along the wall built by Asian architects. Using a precision lattice of bamboo canes and constructed on un-flattened land, the building is considered a master-class in how to blend rustic and modern forms. Simultaneously fragile and strong, one reviewer said it looked like it was literally 'built from the forests of Asia'. That artistic success sparked a string of commissions in China, where he finds the approach to work more flexible than at home. 'In the beginning, they say, 'The building should be done in six months, or something like that.' I never say no,' he says, laughing. 'The important thing is to work together on the problem and become friends with a common goal. We learn, we eat and drink together and become a team. At the last minute, they abandon this crazy schedule. It's very different in Japan - if a client says the job should take one year, it is exactly one year.' Kuma's preference for working in China is not shared with many of his Japanese contemporaries, including Kazuyo Sejima and Ryue Nishizawa, who this year won the industry's top award, the Pritzker Prize. This surprised many, who thought Kuma's talent had been overlooked. Sejima and Nishizawa focus on Europe and the US, but Kuma's portfolio takes him increasingly to Shanghai and Beijing. 'Chinese culture and our philosophy is a good match,' Kuma says. 'I wasn't sure that the Bamboo House would be accepted there, but Chinese people loved it, and we went from there. 'My first impression of China was that it was full of cities of ugly skyscrapers. But younger Chinese architects love the older traditions and want to recover them,' he says, recalling conversations he had when working on the project. 'They feel sympathy for Japanese traditions because the old Chinese traditions remain here - the culture of China before Mongolia and the Qing dynasty. In Japan, we've inherited them so we can give them back.' But there are problems. 'I want to use wood in China, but the quality is bad - they've forgotten how to use wood there.' In both countries, architectural rules follow 20th century tradition, he laments. 'That will kill the uniqueness of small spaces, if we let it. I want to do small projects - to make people reconsider space. Small streets are so very important. Mitsubishi and the other big developers don't want to do that because they put profit first.' Fresh from the triumph of the Sanlitun Soho development, and Opposite House (1999), a six-storey boutique hotel, Kuma is working on the Museum at The China Academy of Art, in Hangzhou. Set in a tea field, the project is the sort of challenge he relishes. 'Sometimes the reality betrays the drawings you've done in the studio, so you have to travel to the sites to see what's going on. And that's very exciting.' Kengo Kuma (left) Favourite Building: Falling Water, Frank Lloyd Wright Favourite City: Beijing Favourite architect: Louis Kahn Wants to be remembered: 'As the man who shifted the direction of Japanese architecture.'