A couple of years ago, Studio Ghibli producer Yoshiaki Nishimura brushed aside the idea of hiring a female director at the legendary studio. Talking to the Guardian, he blundered on about women being the realistic sex and not idealistic enough for fantasy. With this ambitious debut, Mari Okada – a woman directing in the predominantly male business of Japanese anime – proves Nishimura wrong. Heart-meltingly lovely in places, with some cracking battle scenes, her film is set in a universe of dragons, ancient clans and medieval-looking armies familiar from JRR Tolkien and George RR Martin.

Maquia is a female-centred story focusing on a blond-haired race of ethereal waifs called lorphs, who live for hundreds of years peacefully weaving tapestries (they strongly resemble the elves from The Lord of the Rings and, confusingly, all look alike). The story’s heroine is Maquia, a melancholy lorph snatched during a raid by soldiers. Abandoned in a field, she finds a human baby, the only survivor of a massacre. (Maquia prises open his mother’s fingers, stiff with rigor mortis, one bone crunch at a time.) Adopting the boy – a child raising a child – Maquia moves to a sleepy village. The animation here is dazzling: wheat glows golden in the fields; a dog bounds with the bliss of being able to run free on a warm day.

Slowly, it dawns on Maquia that she will outlive her son, that while he will age in human years, she will be a teenager for decades. It is a poignant set-up but, disappointingly, Okada’s ideas about motherhood don’t cut as deep as they could. Is this a film about the forbearance of mothers? The anxiety of not being up to the job? Or a parent’s never-ending fear of losing a child? The film whips through the years without much in the way of an answer and the sticky sentimental score doesn’t help.