Busy and strange, Japanese animation ChaO imagines a world where mermaids, mermen – merpeople? – commune regularly with humans, and where a lowly designer working for a shipping company becomes the romantic focus of attention of the daughter of the king of the sea.
Make sure all your wits are primed when approaching this one, the plot details arrive at furious speed at the beginning – a fairytale princess, a fight with a monster, a mermaid, fantasy tales read in a book by an impressionable young man – before things settle down a touch as dogged reporter Juno finally tracks down his man and gets his scoop: the story behind the famous coupling of Stephen and mermaid ChaO.
Designer Stephen was the guy who invented the propeller that didn’t harm marine life – an impeller really – after king of the sea Neptunus had appeared on the TV news to complain about the carnage current designs were wreaking. It was around this time that Stephen first became entangled with a mermaid princess, who swore eternal loyalty to him and asked him to marry her.
Apart from being quite forward, ChaO is, in essence, the old-school loyal Japanese wife – twittery, dedicated to her man – though Stephen is not as sure about the relationship as he might be. Sure, she’s babelicious, on the rare occasions when her fishy body transforms into a human one. But who wants a relationship with someone who eats electric eels for breakfast? Can a human and a denizen of the sea have anything in common?
It’s a boy wins girl (accidentally), loses girl (incidentally) and then eventually gets a grip on himself when memories of his childhood come flooding back when a life-defining event on his parents’ boat primed him for everything that’s happened.
That isn’t the half of the plot, which has the framing device of reporter Juno trying to get his story, as well as various digressions to the aquatic realm, and thinks nothing of suddenly throwing a gigantic robot, or fishermen being trapped underwater, or a car chase, into the plot. There’s also a sizeable subplot about Stephen’s friendship with Robert, an inventor, just to add another layer.
Moody, complex boy, pure subservient girl isn’t going to shatter any stereotypes, but the human/mermaid liaison might be a parable for the mixing of the races, if you choose to look at it that way, though director Yasuhiro Aoki and writer Hanasaki Kino (who also wrote Children of the Sea) don’t insist on it. And various jibes aimed at ChaO – what red-blooded male would want to be with “a fish”, in essence – are subsumed by the vast amount of plot.
The busy and buzzy, unconventional and painterly animation style sits with other work by animation studio 4˚C, founded in 1986 by Eiko Tanaka and Kōji Morimoto and since then a distinctive presence in national and international animation – everything from 2004’s Mind Game to 2019’s Children of the Sea, with Princess Kaguya (2013), All You Need Is Kill (2025) and Lord of the Rings: The War of the Rohirrim (2024) probably its biggest hits to date.
If none of these mean anything to you, ChaO does also clearly owe something to Studio Ghibli – characters with massive heads pop up – and there’s also an emphasis on extremes: the very ugly, the very fat, the very sexy. Mostly, it’s the fabulous detail that draws the eye and its “one for young and old” approach to storytelling sits it alongside Ghibli too.
It’s a cute story, a bold piece of world-building and a showcase of high end animation. And all done in a tight 90 minutes!
ChaO – Watch it/buy it at Amazon
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© Steve Morrissey 2026
