Mannequins mingle with the visitors at Yohji Yamamoto's retrospective at the V&A

Anyone who still harbours the illusion that Japanese fashion is obtuse and largely a closed book to western eyes can do no better than visit the V&A between now and 10 July for an eye-opening - and, indeed, mind expanding - experience.

In a stark white space with a barrage of high octaine lights - a strong contrast to the normal subdued lighting by which costume collections are illuminated - the exhibition of the work of Japanese fashion designer Yohji Yamamoto has a great sense of energy, as befits a trailblazing revolutionary who has been instrumental in changing so many of our attitudes to how we dress.

It also has a marvellous and very unusual air of casual randomness particularly in how the mannequins are grouped. There is no them and us, object and beholder here; the energy flows across the animate and inanimate, between the mannequin and the visitor - who is free to join any group, walk through it and even, perhaps, touch the garments. It all seems that casual and, above all, accessible.

This idea of freedom and interplay is continued in the main body of the museum with little groups of mannequins popping up in unexpected galleries, in conversational groupings, and when you come across them your first split-second reaction is that they are visitors like you, only infinitely better dressed. It is a ruse to demystify the Japanese fashion aesthetic which Yamamoto and other Japanese designers brought to the west thirty years ago. For a non-specialist audience it works well, as do his rapid life-size sketches on the white walls of nude women waiting to be clothed in the garments on display. Along the walls are television monitors that show excerpts from Yamamoto's fashion shows, films and performances and the classic advertising photographs - pre-eminently by Paolo Roversi and Nick Knight - that are as outstandingly original today as they were when they first appeared.

And the clothes! Anyone who still believes that Japanese dress comes only in black will be surprised and I hope delighted by the brilliant colour of many of the ninety garments on display. Sunshine yellow, magenta, scarlet, vivid grass green and sky blue join with black, white and cream in garments that in character run from the almost casual to the monumental, with jumpsuits as elegant as ball gowns and coats as soft and enticing as your grandmother's shawl when, as a child, you had a bad cold.

Shapes are as simple as a a reed or as voluptuous as a summer thunder cloud but, either way, they always have the total authority of the hands of a master. In those hands street sweats and fifties extravagance come together in timeless clothes that hide their complicated cut and sophisticated artistry behind a facade of accessibility and agelessness. Cotton, velvet, boiled wool - all the trademark fabrics are on display here, in clothes of an apparent simplicity that is, of course, an illusion. If any clothes can be called cerebral, these are the ones.

What I find so refreshing and inspirational about this exhibition - more an encounter between an individual creator and a great cultural institution than the pompous statement that fashion exhibitions can so often be - is the sense of mutual joy and respect that resonates within and around it; this is due to the approach of Ligaya Salazar, the curator, which is fresh, enthusiastic and bold, just as the work of Yohji Yamamoto has always been. It also has the power of his intellectual curiosity and refusal to allow anything to inhibit his creativity. Yamamoto flies free and so will the spirit of the visitor to this delightfully fresh exhibition, which really is one that should not be missed.

Colin McDowell is a fashion historian and author of many books on the subject, including Fashion Today