Choosing which films to see out of the hundreds at the BFI London Film Festival is never an easy task, but one key bit of information definitely helps me prioritise – whether the film’s already got a UK distributor or not. I always pick at least one foreign film or documentary that I may never get another chance to see, usually from Asia, often from Japan. They’re safe bets to me, considering the country’s rich cinematic history, and they provide refreshing breaks from Eurocentric perspectives. My personal opinion is that many modern Japanese cultural products, from anime to music to cinema, thoughtfully mix Western influences and Eastern values so that the experience is both enticingly unique and broadly accessible.

This year I chose director-screenwriter Kenji Uchida’s entertaining tragicomedy Key of Life, a Japanese-style riff on Trading Places in which Sakurai (Masato Sakai), a down-and-out actor, opportunistically steals an amnesaic’s identity. Sakurai’s life is in shambles – he owes everyone money and the ex-girlfriend he still loves is engaged. Likably pathetic, he even fails at committing suicide. When Kondo (Teruyuki Kagawa) slips and hits his head in a bathhouse, a shortcut for restarting Sakurai’s life literally falls at his feet. It’s extra-lucky that Kondo happens to be quite wealthy. Kondo-as-Sakurai chances upon a bit of luck too in befriending Kanae, a nerdy magazine editor, at the hospital. She is on an endearing-yet-vaguely-pitiable mission to get married before her ill father dies, and discovers that it’s convenient to get to know someone while he is trying to rediscover himself. It’s all fun and games until the real Sakurai stumbles across the source of Kondo’s wealth – it turns out that he’s an assassin for the mob, and his last job wasn’t quite finished… thus the fates of these three previously isolated figures are suddenly tied together, and they’re left testing when their collective luck will finally run out.

The world the film portrays is wacky, yet recognisably modern and cynical; apart from the main trio, everyone makes selfish decisions that destroy relationships and are largely driven by pride and materialism. That backdrop is vital, as it facilitates us rooting for these naive principal characters while they earnestly fumble through these unusual circumstances. We trust them enough to go along for the ride, happy to be surprised at the twists and turns.

But most importantly, there’s plenty of laugh-out-loud moments as the two men play with their new identities. Most of the credit goes to Kagawa’s bravura performance as Kondo, deftly switching between the cold, professional assassin to the vulnerable amnesic; Sakai seems outclassed, too much of a ham, but in fairness, his character is supposed to be a failed actor. Key of Life orchestrates its many tonal shifts skilfully, evoking an enjoyable range of emotions. Uchida’s well-crafted, well-executed comedy is well-worth a watch. And next time you’re perusing a film festival programme, keep an eye out for good foreign films without distribution deals.