A girl, a timer, and a wall.
YUI is the first animated short film created with Comfy Agent by well-known AI animation artist 852話 Hakoniwa. The story has been in Hakoniwa’s mind for a long time, since she started working with artificial intelligence. Today, we would like to share how she created it with the ComfyUI team.
Our story with Hakoniwa
We got to know Hakoniwa in the community in early 2023, and met her in Tokyo in 2024. She has been a passionate artist in the diffusion model community in Japan, and has always been one of the first people to try out open-source models and workflows. Her techniques shine very differently because of her own style.
Long before AI, Hakoniwa was a freelance illustrator working under the name meola. In the early days of Hatsune Miku and the Vocaloid scene, she took illustration commissions from Vocaloid producers, and also worked on video production. She composed music as a Vocaloid producer herself and contributed lyrics as well. She then kept making small indie games on her own.
In July 2022, she encountered Midjourney and was stunned. She saw a chance to bring AI into her own game development. At the same time, she felt that the concept art and background work she had kept doing on the side might disappear as AI arrived. She decided to steer firmly toward working with AI, and she has been one of the first to try new models ever since.
Hakoniwa has a strong passion for animation, usually in Japanese style. And 70-80% of her AI video work has been generated in ComfyUI. Right now, she is also co-running AndIdea, a Tokyo-based AI company that handles everything from animation production to generative AI adoption support, consulting, and development. Here is a project we did together two years ago: artwork displayed on event signage in Harajuku, Tokyo, filmed with a real camera.
The Challenge: A story about a girl and the wall
When we were first about to release Comfy Agent, Hakoniwa was the first artist we talked to. After we mentioned the vision to help with “craft” in the creative process, Hakoniwa came back with something more than a product demo. She said “there had been a story I’ve wanted to create for a long time”, and it was about her understanding of storytelling.
We immediately wanted to do it together, as a challenge but also a celebration for both her and ComfyUI. And here it is, the behind-the-scenes story of YUI.
How the character YUI got her look
The main character’s name is YUI. It comes from the last three letters of ComfyUI. Hakoniwa told us there is more in it: 結 means to tie, to connect, and also for effort to bear fruit. “I found YUI within ComfyUI,” she wrote, “and through her, I found new possibilities.”
She was not always YUI. We did 2 versions of characters, and 5 variations of outfits, from option A to option E.
The first protagonist was HIBANA, a red-haired girl Hakoniwa created two years ago in just a few hours. HIBANA was the base of the demo, and from there the character-making with Comfy began. We redesigned her around Comfy: a yellow and purple palette, and a C-shaped logo charm on the zipper.
She mainly used GPT Image 2.5 through the Agent for character design and stills
Video Production
YUI realizes she is the protagonist of a story. And as a red timer appears in her world, this world ends in three minutes. She runs to the edge of the world and finds the fourth wall.
Such a story of a girl escaping and fighting the world involves a lot of highly dynamic and complicated scenes. The artist needs to put a lot of ideas and care into composition, environment, character pose, movement, expression, and overall pacing. “That’s where the creator’s personal taste really shines through,” she said.
The storyboard and the character sheet were also a big part of the preparation.
And the world did not end. In the film, the timer freezes at 0:01 for about fifteen seconds and never reaches zero. The story doesn’t stop there either: it continues into the making-of video, which shows how YUI was made.
Behind the scenes
What we liked is that the artist does not hide the work. Here are a few numbers from the video, stated by Hakoniwa:
About 200,000 Japanese yen total cost, not including labor.
Three days of focused work by one person.
About 2/3 of those three days went to generation (with the help of Comfy Agent) and 1/3 to editing.
From start to finish, the whole project took 7 to 10 days, including the back-and-forth with Comfy, the character-making, and waiting time.
HIBANA, the character she designed two years ago, took only a few hours and is not counted in these numbers.
And Comfy Agent was helpful in these areas:
Regenerating shots. In the rough cut, she wanted to smooth the transitions and fix moments where the visual story was unclear. The final film runs 4:20. Regenerating single shots is the constant chore of a film like this. The Agent builds the workflow and runs it, and she moves on to the next shot.
Comparing models. She compared video models such as Wan, MiniMax H3 and Seedance on the same shot and picked the winner per shot. The main film was made mostly with Seedance 2.5, and the making-of video with MiniMax H3. Doing that comparison by hand takes a lot of time. With Comfy Agent it became a step in the loop. She did the same for upscalers, shown side by side in the channel.
Quality checks. She used the Agent to check outputs and to pull YUI closer to her official character sheet. Consistency is what breaks AI animation. She told us the hardest challenge she knows is a coherent multi-character sequence where nothing falls apart.
Sketch-guided composition. She often used hand-drawn layouts to steer the framing, then went through trial and error until, in Hakoniwa’s words, “each shot matches the intended direction.”
The pattern is simple. The Agent took the repetitive labor, so the artist could spend her time on the actual review, the creative choices, and discussion: which take has the right energy, which face reads as panic, when to stop.
Finally, here is an emoji pack that Hakoniwa created as a gift to the audience and the community.
YUI is the first short animation film made with Comfy Agent, and there will be more.
“The story continues,” as YUI says in the film.
The next one could be made by you.
As always, enjoy creating!