Kyoko Miyake’s documentary explores the phenomenon of pop idols and the people who worship them in Japan, which is to say it’s about mostly male otaku of a certain age fawning and obsessing over teenage and pre-pubescent female J-pop singers. In doing so it follows an idol-on-the-rise, Rio Hiiragi (know to her followers as RioRio), as her career begins to take off, and also weaves in plenty of footage of adult men going wild at small-scale concerts, as well as decidedly creepy behaviour at fan meet-and-greets. The director allows the audience to form their own opinions on this behaviour, though there’s little explanation for western audiences who may be unfamiliar with Japanese culture; this is a country where youthfulness and cuteness is celebrated in many different ways, after all, and the film never properly sets out how idol worship sits within that culture, or whether many people in Japanese society have linked it to paedophilia. I’d have liked to have heard less from the middle-aged male otaku and more from the psychologist, whose many concerns about the way young women are depicted in Japanese culture are fascinating but never fully explored by the film. This is an intriguing documentary, but also frustratingly slight. (**½)