The bouncy pop song that opens Mirai is not necessarily a pointer to the rest of the film but sets up nicely the scenario of the happy couple expecting their second child. Returning home four year old Kun meets them and with some curiosity is introduced to his new baby sister, Mirai.

Kun is soon – he perceives – competing for attention, as Mirai takes up much of his parents’ time complicated by dad not getting to grips very well with looking after the baby, the house, Kun and working at the same time.

Now Kun has had something of a spoiled life so far, basically he’s a brat, and reaches the end of a very short tether takes things out on Mirai, to then be scolded by his mother. Out in the garden feeling sorry for himself he’s suddenly transported to another world where he grows a tail and the family dog takes on human form.

This is the first of several interludes which whisk Kun away to encounter his family’s past, present and future. Stories or parables that he could use to define his character as he takes those faltering steps beyond childhood, and into a complicated and sometimes unforgiving adult world. So the basic premise and narrative of Mirai are pretty straightforward, the animation its scope, ambition and execution however are anything but.

Through spectacular sequences and skilful editing – the jet engine cue when Kun meets his grandfather blasts the viewer in to the seat – the viewer and Kun are transported to places and situations with unbounded imagination. Whether he’s swimming with fishes, a wilful partner wrecking a house, or placed in a bizarre hellish train station the animation is spellbinding.

But this isn’t all on a grand scale as director and writer Mamoru Hosoda examines the humdrum of family life as they discuss their issues over coffee and cakes or Kun frustratingly learning to ride a bike in the park. In fact much of the film takes place in the family home. A curious building on three tiers that looks thoroughly modern in all aspects, juxtaposed with their respect for the ancient tradition of displaying a set of dolls for a girl.

The film is an absolute delight broaching quite heavy subjects but never losing the innocent curiosity of a child’s eye as Kun struggles to understand his changing circumstances.