Falling seriously ill, like falling in love, can happen all of a sudden – although this film is not exactly about either. Drive My Car director Ryusuke Hamaguchi’s new movie, co-scripted by Hamaguchi with the Franco-Japanese screenwriter Léa Le Dimna and his first not set entirely in Japan, is a bold and high-minded if rather pedagogic work that spreads itself over three hours. It’s tender and sometimes beautifully made, but also contrived and occasionally features some too-good-to-be-true caring characters. Frankly, it’s rather precious.

Hamaguchi and Le Dimna have taken as their starting point the nonfiction book You and I: The Illness Suddenly Get Worse by Makiko Miyano and Maho Isono, a meditative correspondence between a philosopher and medical professional on the subjects of love and mortality. Hamaguchi has opened this out to create a drama set in Paris and Kyoto, and it’s incidentally hard not to suspect that Hamaguchi, like many a celebrated movie director spending so much time on the international festival circuit, has been led to create an uneasy international mixture.

Marie-Lou (Virginie Efira) is the director of a private care home in Paris called the Garden of Freedom, where they practise a care technique called “humanitude”, a time-consuming patient-centred approach that exasperates old-fashioned nurse Sophie (Marie Bunel). It needs more staffing facilities than the home is prepared to provide and, in any case, Marie-Lou has a bad habit of being patronising to those who question her. For all that, there are some lovely scenes with caregivers and patients, and these observant, unfussily compassionate moments are where the film works best.

Marie-Lou is stressed and overworked, and her life is upended when she encounters an autistic Japanese teen called Tomoki (Kodai Kurosaki) in the street, apparently lost; he is being looked after by his grandfather, Gorô (Kyōzō Nagatsuka), an actor in town performing in an experimental piece about psychiatric care in which Tomoki is encouraged to take part if he feels like it. The show is directed by Mari (Tao Okamoto), and her stylish calm and intelligence entrances Marie-Lou; they are clearly on the verge of an intense friendship and perhaps more, although the film is reticent on this last point.

Marie-Lou comes to a performance, stays for the Q&A afterwards and reveals herself to be fluent in Japanese, asking questions of Mari in that language which touch on Mari’s very serious illness. Some in the audience rather plaintively – and understandably – call for the conversation to be in French, though this film comes close to being insufferable when Gorô solemnly tells everyone that their exchange was so intimate and meaningful that the audience should be content with simply sensing that.

Mari and Marie-Lou talk all night. They go to the care home to hang out and have a long conversation in the break-room, complete with teacherly things written on a whiteboard: about how capitalism works against care, destroys the environment on which it is a parasite and will eventually destroy itself. The pair go on a trip together to Kyoto, where Mari’s condition – with a foretold suddenness, the predictability of which doesn’t make things any easier to bear – gets worse. Marie-Lou invites her to come back to live in the care home as their physical therapy director, and if there are any issues attendant on hiring someone about to die, and moreover encouraging the residents to form a bond with her, this film is evidently not aware of them. (An elaborate earlier plot point about opening up rooms for caregiver employees to live in may have been intended to facilitate this development.)

All of a Sudden works best entirely outside the exotically overwritten, overthought bond between Mari and Marie-Lou. The realist set pieces are very moving, showing us patients with dementia surrounded by their families, and also showing us, often with photos of their younger selves in demanding jobs, how these patients have changed. The film’s high concept is a little self conscious.