Turtles Are Surprisingly Fast Swimmers is an off-beat, urbane comic gem about loneliness, normality, friendship, and spies, with a charming, low-key performance by Juri Ueno.

Suzume Katakura (Ueno), a twenty-something housewife, is bored. In her eyes, she's the definition of ordinariness - ordinary looks, an ordinary husband, and an ordinary apartment, where she cooks, cleans, and does laundry in an ordinary way. Even her favourite food is ordinary; a ramen that both her best friend and the ramen shop owner think 'lacks character'. Suzume feels that she is destined to go completely unnoticed: strangers often treat her as invisible and her husband, who's always away on business, only calls to check on their pet turtle (who, it ought to be said, we don't actually see doing much swimming, surprisingly fast or otherwise).

Since they were at school together, Suzume ('sparrow') has constantly been overshadowed by her best friend Kujaku ('peacock'). Back then Kujaku's book file was covered in cool Bjork and Oasis stickers, while Suzume's file carried stickers with dorky, childish pictures. Looking back, she reflects, 'poor taste in stickers, poor taste in life'.

One day, however, the monotony of her existence is finally broken. While walking up the same 100-step seaside stairway that she's been taking ever since childhood, Suzume finds herself having to quickly duck to avoid an avalanche of apples. Lying on the floor, Suzume sees a tiny advertisement stuck to a lamppost - 'Spies Wanted! Call for details'.

Turtles Are Surprisingly Fast Swimmers is the second film by writer/director Satoshi Miki, a comedy filmmaker who has now shot to prominence with the recent success of Adrift in Tokyo. Miki always spreads the humour very evenly throughout his films and barely a scene goes by without something clever to laugh at. His style may have been influenced by the Japanese TV variety programmes on which he honed his writing talents, but the comedy of Miki's films is far more subtle and irreverent than that of these shows. Some of the biggest laughs in Turtles come when Suzume is discussing squids getting trapped in sinks with a plumber, and when she's sumo wrestling with her dad. (Ah, ok - the latter of these may not be out of place on a variety show. But generally, the humour is very subtle).

Turtles is impossible to divide up into a beginning, middle, and end. It's the characters' bizarre tangents and nonsensical exchanges which gently drive the evolution of the unusual narrative and themes. Despite being about spies, there is no attempt at suspense - instead Miki cleverly weaves the film's comic episodes in and out of each other in a way that leaves the viewer constantly questioning the film's false realities. Turtles is also visually very striking. Suzume might be bored with her life, but her 'ordinary' apartment is full of such bold and beautiful colours that it's impossible for the viewer to feel the same way.

In the end, a film with such an off-beat narrative, interesting contrasts and clever wit could only work with great acting and thankfully Turtles delivers this throughout. Eri Fuse and Ryo Iwamatsu provide great performances as Etsuko and Shizuo, the spies Suzume meets when she responds to the tiny advertisement. They're a married couple who, despite a doing a bit of karate sparring, don't appear anything like real spies. But then again if they did, they probably wouldn't be very successful, as Suzume figures. Etsuko and Shizuo place their trust in Suzume, purely because she is so ordinary and not only do they give her 'spy training' but also 500,000 yen for 'operational expenses'.

In the role of Suzume, Juri Ueno excels. Her comic timing is acute, and she shows a willingness to be silly, in a way many actors never do. Since Turtles, she's become very popular domestically in the manga-adapted TV series Nodame Kantabire. Her most endearing moments in Turtles come when, after becoming a spy, Suzume returns to her 'ordinary' life. However, from Suzume's new perspective she is no longer ordinary, she is now being deliberately inconspicuous.