You fear the worst when you discover that this is an anime about a high-school tutor forced to choose which of his five quintuplet students to marry; will it be something flagrantly oblivious to recent #MeToo advances? But Masato Jinbo’s film is actually a fairly charming, if stridently sentimental and moralistic romantic fantasy that, with its clever structure, even manages to pick at the mysteries of identity.

The story is the culmination of the Quintessential Quintuplets TV series, an adaptation of the 2017-2020 manga of the same title. One mitigating factor is that Uesugi (voiced by Yoshitsugu Matsuoka) is approximately the same age as the five sapphire-eyed quins he is chaperoning as the end of the school year approaches. Everyone is looking ahead to their plans for the future, but there is the annual school festival to get out of the way first. The five siblings are equally moony over their tutor, and gathering them together, he admits he has feelings for them, too. But he promises to choose one by the time the three-day festivities are done.

Given how Jinbo flits between time frames, and in and out of character’s thoughts, following the identical quins isn’t easy at first. But the film quickly becomes an elegantly hormonal Rashomon, tracking each one in turn over the three-day period, carefully individuating each to the point it begins to graze the old nature/nurture chestnut: how flighty Ichika (Kana Hanazawa), already a famous teen actor, can be so different from the stern but protective Nino (Ayana Taketatsu); ditto overcompensating people-pleaser Yotsuba (Ayane Sakura).

Weaving in a thread about the girls’ biological and adoptive dads, the business of settling this love hexagon is conducted with the same vehement seriousness as the Shogun picking clans in a medieval samurai drama – only with copious blushing and Uesugi gasping like he’s been run through every time he kisses someone. It largely avoids ickiness, apart from the bosomy waterpark intro; in fact, its insistence on the essential fallibility of the teacher, that they are there to learn from their students as much as vice versa, shows sensitivity. Like Uesugi’s ability to distinguish between the girls, The Quintessential Quintuplets looks beyond the surface.

• The Quintessential Quintuplets Movie is released in cinemas on 7 December.