With the demise of Satoshi Kon (‘Tokyo Godfathers’) and the retirement of Hayao Miyazaki (‘Spirited Away’), Japanese animation now lacks a signature filmmaker: can first-timer Yasuhiro Yoshiura take up the mantle with the ambitious sci-fi epic ‘Patema Inverted’? He shares Miyazaki’s facility for creating fully imagined, richly detailed worlds. This is a high-concept tale about gravity going haywire in a post-apocalyptic Earth, where underworld dwellers fear going up top because they’ll float off into the sky. Meanwhile, surface inhabitants keep their feet firmly on the ground and guard their authoritarian community where flight is banned. It’s not an altogether original idea (see the Canadian fantasy ‘Upside Down’ and British stop-motion short ‘Head Over Heels’), but the film does well on its bonkers premise. It offers a slightly functional romance on opposite sides of the gravitational pull – plucky Patema’s the girl from down there, dreamer Age her protector when she ventures up above. It’s impressive but not dazzling. Miyazaki would have given the action more thump and Kon might have gone that bit weirder, but this still heralds the arrival of a promising talent.