Fish Out of Water: ‘ChaO’ Director Yasuhiro Aoki Dives into Studio4°C’s Acclaimed Movie [Exclusive]

This article was written for the September-October ’25 issue of Animation Magazine (No. 352).

Yasuhiro Aoki wants to challenge himself. A veteran animator currently at Tokyo-based Studio4°C, he previously co-directed Batman: Gotham Knight and contributed animation to Psycho-Pass: The Movie — atmospheric and moody features that worked with shadows and darkness. Aoki has swum against that tide for his latest feature, the Annecy-premiered ChaO, which ushers in bright colors and kinetic visuals. “When I embark on a new project, I like to do something that is the complete opposite of what I did previously,” Aoki explains.

“Typically, in anime, there’s a coherence to the world. We went out of our way to avoid that — which is why we created characters that are a bit thin or have rounder bodies.”

— Director Yasuhiro Aoki

ChaO is Aoki’s debut solo directorial effort, and helming the film brought new experiences and hurdles to overcome. “Making a feature is a long process, so there’s an element of endurance,” reflects Aoki. “Luckily, the tension and excitement in that didn’t dissipate, and I felt invested throughout.”

Responsible for some of Japan’s most idiosyncratic and internationally minded animated features — such as Mind Game and Tekkonkinkreet — Studio4°C has long been synonymous with innovation and thinking outside of the box. Its name derives from the temperature at which water is most dense — so perhaps an aquatic escapade was an inevitability.

Interspecies Romance

ChaO tells the tale of Stephan, a down-on-his-luck inventor living in a fantastical future Shanghai — where diverse species beyond just humans walk alongside one another. Swept underwater one day by a giant wave, he wakes in a hospital bed to find those around him talking of love and marriage. His savior from a watery demise is Chao, the mermaid princess. Thanks to a purported romantic confession, Stephan and Chao are betrothed to be married — despite the fact that Stephan can’t recall having uttered a word to her or even having made her acquaintance.

The film’s Shanghai setting sets ChaO apart from its anime stablemates. “I think the way we approach a film’s setting at Studio°C is very unique to us,” suggests Aoki. “It’s not so much about the specific place but about the perspective within it. For example, a corner of the town, or atop the electric lines that hang above the city. It’s a way for us to show something different, from a unique angle.”

Shanghai’s atmosphere is a far cry from the domestically all-too-recognizable Tokyo, and that difference attracted Studio4°C to pursue the locale. The team went to Shanghai during preproduction to location scout, only to find themselves overwhelmed by the busy feel of the city. “There was so much going on, and we really took that in,” says Aoki. “We had these mismatched characters that we had to build a coherent world around, so it was about working out how to use Shanghai’s busyness and clutter to enhance that.” The aesthetic result is a unique blend. “We wanted to capture a mixture of manga and fantasy,” explains Aoki. “It was challenging for [character designer] Hiroshi Takiguchi (Weathering With You, The Case of Hana & Alice) to create something that at first glance doesn’t cohere but doesn’t feel strange or uncomfortable.”

Chao herself is a particularly fascinating figure, her form morphing and shifting throughout the film’s 90-minute runtime. “Usually, the mermaid remains in one form from start to finish,” reflects Aoki. “I wanted to attempt a character that deforms and reforms into a different thing.” It’s a device that Aoki and his team have thought very deeply about. “Transitioning can be very vulnerable,” Aoki says. “In this case, the character transitions from this big, anime-like character into a scrawny girl, and vice versa. The transition itself is not quite grotesque, but it’s uncomfortable and vulnerable.”

Stephan and Chao stand out in the crowd, but passersby are equally worthy of attention — an enthralling menagerie of creatures cute and colorful. “I like to vary the specifics of characters’ faces, and we took a telephoto lens approach to the environments,” says Aoki. “With that in mind, I don’t really worry about exposition. I’d rather drop the audience into the world and allow them to immerse themselves and explore. It’s a challenge for the viewer.”

These characters come in all shapes and sizes — to fascinating effect when placed together. “Typically, in anime, there’s a coherence to the world,” says Aoki. “We went out of our way to avoid that — which is why we created characters that are a bit thin or have rounder bodies. The film is about coexisting. I hope that the audience sees that diversity and variety is what makes this world so beautiful.”

A standout sequence comes at the film’s midpoint, when Chao dances in the water fountain at the heart of the city. “I enjoy incorporating an element that is pure entertainment,” remarks Aoki. “It’s both a transition between Act 1 and 2, and a transition in Chao as she grows into her own skin. I wanted to show the beauty and confidence in that.”

This fluidity extends to the progression of the film at large, and ChaO is beguiling in its lack of breaks. “There’s something in finding a mutual ground between one scene and the next,” explains Aoki. “Whether that’s mirroring a character’s gesture or movement in the subsequent scene or a sound staying in a certain key, it’s about providing a point of contact from one scene to the next — such that you have a chain of transitions that connect.”

Fish-out-of-water tales have a storied history in anime, with many works having taken direct inspiration from films like The Little Mermaid, Hayao Miyazaki’s Ponyo and Masaaki Yuasa’s Lu Over the Wall. Aoki feels that the universality of trying to communicate across barriers is what makes this tradition endure. “There’s a beauty in someone who doesn’t understand your language trying to communicate with you, and vice versa,” says Aoki. “There’s a nicety and friendliness that is drawn out of a person when they’re trying hard to bridge that. It’s a funny thing — when you don’t have the means to communicate, the best version of yourself comes out. And there’s a relief and joy when you finally understand each other after having this back-and-forth.”

ChaO carries many of the same hallmarks of Studio4°C’s previous works. We’re introduced to a lively cityscape in motion, much like in Tekkonkinkreet, and our hero is a scrawny underdog with an angular and elastic outline. “We’re conscious that there are things that only this studio can do,” says Aoki. “But, of course, when producing a new film, we want something fresh about it. It’s about juggling the two — putting things in and taking other things out — adjusting elements to make something new whilst honoring the uniqueness of what the studio can offer.”

Hand-Drawn Magic

As with many major anime production houses in Japan, Studio4°C is changing with the times in the methods and visuals it employs. “About 70% of the film is hand-drawn,” says Aoki. “But there’s something that the audience enjoys about CG, and I want to allow ourselves to enjoy working with CG. The car chase sequence, for example, was made entirely with CG.”

A line of dialog stands out, as the film’s hero commands a goon harassing his fiancée to “watch movies that make you nicer!” “That line wasn’t in the original scenario, and it just kind of came to me as we made the film,” reflects Aoki. “It came from the heart. I think all films are made with that goal.”

ChaO is an ode to love that could only be conveyed through animation. “With animation, drawing doesn’t happen without someone doing so,” says Aoki. “There’s a power in drawing a line, and that becomes a picture, then an animation — and that requires a lot of passion and thought. When it all comes together — drawing, sound, voice — there is so much heart to it. Live action is easier to assemble, but with animation there’s a process to it. Without someone holding a pen and drawing that line and creating, it wouldn’t have happened. I think animation is a vital tool in telling stories of love, because it starts from one person’s love of drawing.”

ChaO will be released by GKIDS in U.S. theaters early next year. The film opened in Japan through Toei on August 15, following its premiere at Annecy, where it won the prestigious  Jury Award.

With thanks to Juna Shai for interpreting.