From a conceptual standpoint, Mirai plays around in an expansive, awesome sandbox. Writer-director Mamoru Hosoda smashes together tropes of Dickens, Capra, Pixar and Nolan with the glee of a child clanging together toys of different brands and exalting in that creative clash.

Kun is a tantrum-prone tyke who, when we meet him, seems excited to welcome home his newborn sister, Mirai. We find out, though, that Kun was merely eager for his mother and father to return and resume what he believed would be a shower of love upon him. Given the infinitely less self-reliant baby in the house, Kun soon sees himself as an afterthought — his anxiety erupting in anger and, in a couple truly surprising moments, aggression toward Mirai.

Beating a hasty retreat into his vast and vibrant imagination, Kun envisions his dog as a human man, himself deprived of human affection since Kun came into the picture. He discovers a new playmate of his own age who seems like a younger version of someone already in his own life. He finds himself sitting shotgun on his war-veteran great-grandfather’s motorcycle and, eventually, encounters a teenaged version of Mirai, who serves as a sort of Marley to Kun’s small-scale Scrooge.

Using the inner life of a child as his springboard, Hosoda tries to suppose the path by which siblings — once consumed by jealousy — make their way to cohabitation with new arrivals and, eventually, love. There certainly are some lovely moments and imaginative animation in Kun’s mind-bending journey to find the confidence, and conviction, to truly become Mirai’s big brother, but Mirai never quite hits the dizzying heights to which it aspires.

For starters, Mirai could stand to lean more on the side of compassion than, say, a short fuse similar to Caillou, as Kun’s screeching quickly grows tiresome. (Let it not be said a childless man can’t appreciate pop-culture equivalencies that conversations among his friends with kids can provide.) Yes, Kun is young. Yes, kids wail. You don’t need kids to understand that acclimation to change is a process, but it just feels a tad too whittled down to the binary of “calm” and “chaotic” here. In addition, we feel neither one lesson building on the next or that Kun is really learning much. Outside of the final 10 minutes, we don’t see much of a change in him. Despite what he learns in the fantastic voyages of his imagination, Kun often returns in the same shade of “crotchety grumpus.”

And oh, to have had the Japanese track with subtitles and not the English-dubbed version. Jaden Waldman seems to have been given one direction for Kun’s meltdowns — Macaulay with a megaphone. That may match the usual exaggerations of anime anger that we see, but there’s no audible modulation to it whatsoever beyond whimpering and whining and maximum volume. The biggest names in the cast are Rebecca Hall and John Cho as Kun and Mirai’s mother and father. Hall sluggishly seems like she’s simply reciting lines from a piece of paper handed to her at times. Cho brings some life to his character, but even then he – and his story – are reduced to repetitive montages of Mr. Mom-like mugging.

Mirai’s strongest asset is its approach to a depth of storytelling without sacrificing accessibility. The way it addresses wartime violence — and its capacity to affect even those family members who don’t serve — doesn’t cop out on the complexity, and Kun’s climactic slipstream boogie through past, present and future has some affecting touches. (Certainly the animation projected on the big screen will look better than the online screener, which had motion-blur artifacts all over the place.) But for all its boundless possibilities, the version of Mirai made available for review too often feels like an oversimplified, atonal misfire.

Mirai is screening in Indianapolis theaters — including the Hamilton 16 in Noblesville — as a Fathom Event on Thursday, Nov. 29, Wednesday, Dec. 5 and Saturday, Dec. 8. Some screenings are dubbed in English while others are in Japanese with subtitles. Check listings for showtimes.