If The Boss Baby had boasted generous doses of Studio Ghibli-esque insight and imagination, it might have resembled this animated domestic fantasy from Japanese writer-director Mamoru Hosoda. Brimming with sweetness, charm, whimsy and some epic tantrums, it plots the struggles of a train-obsessed four-year-old boy, Kun (voiced by Moka Kamishiraishi), to adjust to the arrival of his baby sister, Mirai; a struggle involving quite the rollercoaster of emotions.

Beneath their vaulting fantasy trappings, earlier Hosoda films such as Wolf Children and The Boy and the Beast exercised a keen grip on family dynamics. Here, he focuses that fascination into a house barely big enough to contain young Kun's dreams and pinballing temperament. When his mum starts work and his dad juggles home work with childcare, Kun's mind breaks through the boundaries of space, time and identity to imagine encounters with re-configured family members (and pets) from his past, present and future.

A Christmas Carol is the obvious reference point for Kun's inner learning curve, though Hosoda honours his child's-eye view with a delicate immediacy of tactile detail and dream-like fancy. The family mutt transforms into a swish prince; a raindrop becomes a glistening time portal.

Though these visions reach for the free-range scope of Studio Ghibli, Hosoda always anchors them in a clear-sighted respect for kids' drives, whether he's depicting Kun's bolshy determination to ride a bike or Mirai's fast-erupting demands. These disparate parts achieve lift-off with a tremendous lightness of feeling and empathy at the climax, where a train station and its occupants shift shape in tune with Kun's hopes and fears. Even if the influence of Ghibli captain Hayao Miyazaki is unmistakable, Hosoda's playful mix of intimate truths and expansive wonders shows a generosity of spirit and sweep that's all his own.

General release from Fri 2 Nov.