As the godfather of technopop, actor, model and soundtrack composer Ryuichi Sakamoto has reached places other musicians barely know exist. Yet, despite having worked with a list of collaborators that includes David Bowie, Youssou N'Dour and Bernardo Bertolucci, Sakamoto remains a shadowy and self-effacing presence.

Barely visible on the unlit platform, he busied himself with banks of tape machines, turntables and digital keypads. The idea seemed to be to whet his listeners' appetite for the melodic material due later in the show by testing their responses (and possibly their patience) with an apparently random assortment of noises. Snatches of Japanese koto music alternated with chunks of tribal chanting or eerie orchestral strings. What sounded like hiss from a faulty amplifier gradually took on rhythm and shape.

Then Sakamoto slipped across to the piano and plunged into the mainstream of European classical music. His first piece was limpid, delicate and somewhat Satie-esque. Then he grew more "romantic", hinting at the ghosts of Chopin - even Rachmaninov or Schumann.

Words and symbols flashed up on a pair of screens behind him - "a massive bundle of letters sleeps in my arms", "a newborn baby" - but it was hard to discern what they added to the performance. Sakamoto may be a cunning synthesist of concepts and cultures, but for that very reason, it's difficult to pin down what he means.

Perhaps that's what has made him such a successful soundtrack composer: writing music for movies means missing bits out and playing down your own identity. Joined onstage by the string quartet Solid Strings, he played Rain, from his Last Emperor soundtrack, then a piece he composed for Wuthering Heights. The first sounded like a formal exercise in Nyman-esque minimalism, the second was windswept, lush and vapid. Excerpts from his opera, Life, seemed technically assured but lacked intensity.

It was as if Sakamoto had passed through but left no trace behind him. Quite an accurate reflection of his whole career, in fact.