WHAT A LONG, strange journey it's been for Ryuichi Sakamoto. A revolutionary Tokyo firebrand in the 1960s, he morphed into a 70s techno pioneer with the seminal Yellow Magic Orchestra, a movie actor in the 80s in films including Merry Christmas, Mr Lawrence with David Bowie, and then Oscar-winning soundtrack writer. He enjoyed a creatively fertile period as a sort of Japanese Brian Eno, collaborating with everyone from rock's wild-man Iggy Pop to Brazilian pop muse Caetano Veloso. Today, he lives in New York as an avant-garde composer of ambient music. 'The global view of cultures is part of my nature. I want to break down the walls between genres, categories or cultures,' says Sakamoto, who has composed soundtracks for directors Bernardo Bertolucci, Pedro Almodovar, Oliver Stone and Nagisa Oshima. At 54, Sakamoto is a long way past his pop idol prime with the Yellow Magic Orchestra. But he's never been afraid to wander far from the mainstream spotlight, and is now collaborating with cerebral German ambient musician Carsten Nicolai, who works under the pseudonym Alva Noto. On stage in Tokyo, the two are a study in contrasts: the classically trained Sakamoto sways and bows in concentration over his acoustic piano as Nicolai stands almost unmoving, like his fellow German electronic pioneers Kraftwerk, coaxing electronic blips and bleeps from his computers. At an interview just days before they wind up a short Asian tour in Hong Kong on Saturday as part of the New Vision Arts Festival, the contrasts are even more evident. The short-haired, blue-eyed Nicolai speaks in the clipped, precise cadences of a scientist, while Sakamoto comes across as more of a dreamer. Neither is sure how they first heard about each other, but their six-year collaboration has been creatively profitable, yielding three albums including the acclaimed Vrioon (2003). 'I'm always looking out for interesting people,' says Sakamoto, describing his friend as an 'energetic minimalist'. 'Somehow I see music as a garden which has a lot of different styles: contemporary, classic, ethnic, Japanese, rock'n'roll and so on. I can enjoy them all and there is space for them all. I can listen to Bach and Iggy Pop, though not at the same time ... Iggy is too loud.' An element of Nicolai's work that attracted Sakamoto was his attempt to turn sound into image: their concerts are dominated by a long LED screen that converts their combination of machine and piano music into visual symbols. Oddly, given his eclectic musical resume, Sakamoto is probably better known among young people in Japan for his environmental and political work. A long-time activist who once hung out with the radical left, he is Greenpeace Japan's most famous supporter, a staunch anti-nuclear campaigner and one of the founders of Stop-Rokkasho.Org, a grass-roots project trying to close a controversial nuclear reprocessing plant in Aomori. 'Well, I'm very worried, politically and environmentally,' he says. 'There is the danger of a nuclear leak and the proliferation of plutonium, which terrorists could steal. Japan has 43 tonnes of plutonium now. That's 5,000 Nagasaki nuclear bombs. The [Rokkasho] plant will produce another eight tonnes a year. What for? Now we have North Korea's nuclear test, so the taboo in Japan is going away and people are talking about [developing] nuclear weapons.' With a thriving nuclear industry in Japan, few local celebrities would stick their heads so visibly above the barricades, and Sakamoto claims his domestic career has suffered. 'Japan has some major corporations and they are major clients of the mass media so of course they hate me. But I'm not worried because I know what I have to do,' he says. 'I feel my responsibility to speak out for my own children and future generations.' Sakamoto is particularly incensed at the way the Earth's resources have been used up. 'Water isn't free any more. Everything's becoming controlled by big corporations. I'm worried about this.' Like many others, Sakamoto's fears for the planet were exacerbated by the September 11 attacks on New York, where he has lived for years. He says he talked endlessly about leaving but decided to stay for the sake of his teenage son, who attends a pacifist Quaker school in the city. 'We were worried about a second terrorist attack, perhaps a nuclear bomb in a briefcase. More than that though, we were shocked that our friends in New York turned patriotic overnight. They started putting out the flags and so on. So we were searching for a safer place,' he says. 'Maybe Kenya or Brazil,' he adds with a laugh. As a German citizen, Nicolai says he shares his collaborator's concerns. 'Our previous government decided we would stop the use of nuclear power, but now it is coming back,' he says. 'I see the danger globally. At the moment we face a war over resources: oil. Many people think atomic power might solve this problem but then the battle becomes for other resources such as uranium, so this is no solution.' Despite their fears for the future, both men prefer to keep their music and politics separate. Nicolai attributes this reaction to his upbringing in East Germany, and Sakamoto to the polemical, angry music of his youth. 'We were radicals,' says Sakamoto. 'I used to think then a lot about propaganda and music. But in the early 1970s when the movements failed, I shut my mouth for 20 years because I was against using music for propaganda. I didn't like the political folk singers of the time.' Sakamoto, who earned a master's degree from the Tokyo University of Fine Arts and Music, says he drifted into electronic music mainly because he couldn't play a stringed instrument. 'I was playing the piano since I was three or four years old so I missed my chance to buy my first guitar. It's just the way things worked out.' Nicolai draws an even more distinct line between his music and his politics. 'For me it is quite clear. I really separate it. Art should be disconnected from any kind of propaganda. Combining the two is very dangerous and it steals a certain power from the art. If you're politically involved you can spend your energy and knowledge, but you have to consider which way you work as an artist.' The expense of moving the computers, piano and specially commissioned digital screen that they will be using in Hong Kong has effectively ruled out a tour of the mainland. 'It is too expensive,' laments Sakamoto. Despite a sometimes hostile relationship between China and Japan, Sakamoto is less concerned about the potential for conflict between them than environmental deterioration on the mainland. 'Neighbours fight all the time,' he says. 'My biggest worry is the environment. That's much more serious than political conflict. China is building 18 new nuclear plants and Japanese companies like Toshiba are helping them.' Ryuichi Sakamoto and Alva Noto; Insen, Hong Kong City Hall Concert Hall, Sat, 7.15pm and 9.45pm, HK$150-HK$450. Inquiries: 2370 1044