The story continues: how 852話 Hakoniwa made YUI, the first animated short created with Comfy Agent

YUI, by 852話 Hakoniwa. Film: 852話 Hakoniwa / AndIdea.

A girl, a timer, and a wall.

YUI is the first animated short film created with Comfy Agent, made by 852話 Hakoniwa, a well-known AI animation artist in Japan. The story had been in her mind for a long time, since she first started working with artificial intelligence.

When we were about to release Comfy Agent, Hakoniwa was the first artist we talked to. We described the vision of helping with the craft in the creative process, and she came back with something more than a product demo. There was a story she had wanted to create for a long time, and it was about her understanding of storytelling.

We wanted to make it together right away, as a challenge and as a celebration for both her and ComfyUI. This is the behind-the-scenes story of YUI.

Who is 852話 Hakoniwa?

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 worked on video production. She composed music as a Vocaloid producer herself, contributed lyrics, and 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. She also 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.

We got to know her in the community in early 2023 and met her in Tokyo in 2024. She is one of the first people to try open-source models and workflows, and her techniques stand out because of her own style. Her passion is animation, usually in a Japanese style, and 70 to 80 percent of her AI video work has been generated in ComfyUI. She also co-runs AndIdea, a Tokyo-based AI company that handles everything from animation production to generative AI adoption support, consulting, and development.

How YUI got her name and her look

The main character's name 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, and through her, I found new possibilities."

852話 Hakoniwa

She was not always YUI. 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 went through two versions of the character and five outfit variations, from option A to option E, and redesigned her around Comfy: a yellow and purple palette, and a C-shaped logo charm on the zipper.

Hakoniwa mainly used GPT Image 2.5 through the Agent for character design and stills.

A world that ends in three minutes

YUI realizes she is the protagonist of a story. A red timer appears in her world, and the world ends in three minutes. She runs to the edge of it and finds the fourth wall.

A story about a girl escaping and fighting the world means a lot of highly dynamic, complicated scenes. The artist has to put ideas and care into composition, environment, character pose, movement, expression, and overall pacing. The storyboard and the character sheet were a big part of the preparation.

"That's where the creator's personal taste really shines through."

852話 Hakoniwa

The world did not end. In the film, the timer freezes at 0:01 for about fifteen seconds and never reaches zero. The story does not stop there either. It continues into the making-of video, which shows how YUI was made.

What did Comfy Agent actually do?

What we liked is that the artist does not hide the work. The making-of video states the numbers, and it shows where the Agent helped.

• Regenerating shots. In the rough cut she wanted to smooth the transitions and fix moments where the visual story was unclear. 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. Doing that by hand takes a lot of time. With Comfy Agent it became a step in the loop. She did the same for upscalers.
• 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 each shot matched 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.

At a glance

HIBANA, the character Hakoniwa designed two years ago, took only a few hours and is not counted in these numbers.

The story continues

Hakoniwa also made an emoji pack 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."

YUI, in the film

The next one could be made by you.