Documentarist Kim Longinotto has, over the years, launched a number of investigations into the social habits of Japanese women. This latest, following the activities of a training gym for female wrestlers, is a concerted attempt to understand those who would go against Japan's apparent preference for all things demure, restrained and prettified where women are concerned.

The Gaea circuit, it would seem, is a homegrown version of the WWF, and its costumes and theatrical grappling are a low-budget fascimile of Western wrestling - no fancy martial-arts and sumo moves here. Introduced first is Nagoya Chigusa, the shock-haired, pugnacious fighter in charge of the training camp, who is also a well-established wrestler. In fact, the first proper bout we get to see is Nagoya, fighting for her team's place in the division, against a grappler who goes under the name of "Lioness Aska", and who appears equipped with a large ironing board. Nagoya, however, is too quick for the Lioness, and sneakily overpowers her with an unexpected mouthful of lighter fuel blown through a naked flame.

Though the drift of the film appears at first to be a not unexpected vision of tough-girl empowerment, Gaea Girls begins to edge into more fruitful areas. Like all good documentaries, the real narrative emerges slowly, and here it reveals itself to be the story of Takeuchi, one of the recruits who has to pass a stringent multi-bout test to prove herself worthy of making her professional debut.

Outside the ring, Takeuchi is a shy, sweet-tempered giggler; inside, she becomes a ball of screaming energy, desperate to impress her coach and promoter. As she is routinely humiliated and reduced to a snivelling, bloodied wreck, Takeuchi's odyssey becomes genuinely heart-rending; but it's all too evident that, in sparring bout after sparring bout, she lacks the sheer bodyweight and strength to make a natural wrestler.

Longinotto and her co-film-maker Jano Williams don't inquire too deeply into the choreographed nature of what they are witnessing; their detached style makes a virtue of letting the fighters speak and act for themselves. But that's a minor quibble into what becomes a moving portrait of a bizarre sub-culture.

Screening tonight. Box office: 0131-623 8030.