Bonne Idee.

In a Tokyo office scheme, a Western practice has transformed an old petrol station into a civilised and lyrical workplace.

Since its foundation 15 years ago by Teruo Kurosaki, the Japanese furniture firm Idee has built up a reputation for original often lyrical design. For their new offices and showroom in Tokyo, Kurosaki chose Klein Dytham, a young Occidental practice working in Japan and responsible for a series of refined interiors for a fashion house (AR January 1996). Scattered throughout the country, the schemes revealed the architects' appreciation of local context and Japanese traditions of simplicity, and also playfulness.

Their building for Kurosaki is at the junction of crossroads in Shimouma, at a point busy with traffic and the tangle of overhead wiring that is characteristic of the city. It reminds you of a Japanese paper lantern; cloudy grey and semi-opaque by day, it glows after dark with coloured light like a beacon. The site had once been a '60s petrol station and forecourt, consisting of two pumps and a two-storey concrete kiosk tucked away at the back - a small fragment of '60s toughness that induced keen nostalgia in the client. For practical, as well as nostalgic reasons, it seemed sensible to retain it as a solid core of private offices. Painted brilliant yellow, its presence is emphasised, enshrined within a new luminous three-storey shed in which the objects for sale constitute pieces of coloured sculpture, and which accommodates a light, airy design studio. Being in fact somewhat fragile, the kiosk had to be independent of the main steel structure which oversails it at second floor level and elsewhere impinges very lightly. Part of the first floor and the staircase are of finely filigreed metal which has the effect of isolating the solid little structure, expressing its integrity and separate function and affording a vertical flow of space. Details like the way handrails are individually strung on vertical steel cables like beads on a necklace contribute to the immateriality of the stairwell, which, as a vertical element in the composition, has an echo on the south side in a two-storey tower of clear workshop space. This is designed for the construction of large objects which can be taken out through an almost full-height wall of rolling shutters.

The plan of the building is irregular, shaped by the line of the roads on the south and west. The main west facade is glazed but shrouded externally from the first floor upwards by a curved screen of translucent polycarbonate. The device leaves the ground floor showroom visible from the road, but screens the first floor meeting space and second floor design studio from the visual busyness outside, making the gleaming white interior seem calmer and more spacious without shutting out daylight. From the outside, you have the impression of shadow puppets as people move backwards and forwards behind the screen. At first floor level, the glazing is partly covered with coloured films and the effect on floors and walls is like stained glass, for the concrete floors coated with glossy white epoxy resin are stained with colour as the light changes and shadows lengthen. The undersides of the corrugated steel decking that supports the floors have been left exposed, again simply painted white and - kept free of lighting and other fixtures - are used as large reflective planes off which to bounce uplight. At night these illuminated surfaces glow through the screen as you look up at the building.