Maybe you know Japanese animation production house Studio Ghibli from its spellbinding 2001 crossover hit Spirited Away, from the oddly familiar Totoro character on its insignia, or for inspiring broken records in the twittersphere. But even if these mentions meet only with your indifference, I invite you to be charmed by this feature which unfolds unhurriedly in the 'real' world. Unusually in the Ghibli canon, folkloric or supernatural creatures aren't part of the drama, but there is plenty of mystery in this vignette about a lonely adolescent girl's summer.

Affected by asthma and social anxiety, Anna collapses and is sent by her well-meaning foster parents to recuperate by the sea with their relatives. Although the retreat begins unpromisingly, she discovers an apparently abandoned mansion, and takes a shine to Marnie whom she finds there. The storybook feel of proceedings is matched by Anna's proficient pencil-sketches, which remain secret like her new friendship. Indeed, this is an adaptation of Joan G Robinson's young adults' book, with the narrative transplanted from Norfolk to Sapporo, Japan.

There are nice touches of characterisation – the visual idiosyncrasies of Sayaka, the bantering aunt and uncle – however, Anna herself is harder to warm to. Perhaps, to quote her foster mother, this is because of her 'ordinary face' that doesn't register much expression. Anna also goes full pubescent and says 'I hate myself' on two occasions – I imagine these factors are what have made some critics find the film cold or impenetrable. But communicating a sense of detachment is fitting for a film set in adolescence, and Anna's character arc doesn't leave her where she began. Golden-haired Marnie is presented as a bit of an ideal, appropriately for someone whom we at least sometimes believe to be imaginary.

Themes of friendship and forgiveness are traceable, but even more 'felt' is the aforementioned adolescent experience – if you've experienced that unexplained sadness and alienation, there'll be something familiar here. The 'in-between places' of consciousness often feature in Ghibli films, none more than in Marnie: between reality and dreams, internal and external worlds… even Anna's uncertain ethnicity and gender-neutral appearance play their part. The soundtrack, in its fairytale way, highlights the unreality of moments we're expected to think Anna dreamed.

It's a different Anna that returns from this summer retreat, not necessarily due to the sea air, or 'the wind' that was originally expected to salvage her health. There's a poetic aptness to that – Studio Ghibli is named after the Mediterranean wind that founder Hayao Miyazaki hoped the studio would emulate by providing a breath of fresh air to the industry. He has now retired, and the company's future is uncertain. Although unrepresentative of its output as a whole, Marnie would be a worthy final feature. Minor, pastel-hued and relaxed of pace, but magical in the ways that matter.