"Just a Cup of Coffee" — Interview with Talented Filmmaker Yubin Kim

1. How do you define "emotional residue" in the context of this story?

Emotional residue is the trace that stays inside us long after an event is over. When a choice as small as ordering decaf, or pouring in too much syrup, touches the other person's deepest wound, we suddenly come face to face with their entire past. I was less interested in what the two people say to each other than in the silence and distance left hanging in the air afterward.

The floating transparent helmets are the visual form of that residue—the things we carry unseen, that draw us toward others and become invisible walls at the same time.

2. Which specific AI tools did you use during production?

I chained several tools together in order. First I used Midjourney to set the overall tone and draft the visuals. Then I built character sheets for the two leads in Nano Banana, so they'd read as the same people even as scenes changed. I structured the storyboard in Gemini, and handled the overall video work in Kling. No single tool does everything—the key was picking the tool that's best at each stage and connecting them like a pipeline.

3. What was the biggest technical challenge in rendering the floating helmets?

Transparency and consistency. The helmets had to be visible, but the expression of the person behind them had to stay alive too. In Kling especially, transparency and reflection shifted subtly from frame to frame, and keeping the characters' faces from drifting was hard. Locking the character sheets down early in Nano Banana was what kept that drift under control.

4. How did you handle prompting to get such a specific, restrained tone?

At first I used direct words like "love" or "sadness," but the results felt too obvious. So I shifted to describing atmosphere and physical detail—the way they look at each other, glances met and turned away, the faintest tremor—instead of naming the emotion. The less I stated the feeling, the more strongly it lingered on screen. In this film restraint wasn't just a mood; it was a working principle, and it started at the prompting stage.

5. Did the AI tools ever generate an unexpected error that you kept in the film?

The ending of this piece actually came from exactly that. The film has a two-part structure with a time-reversing transition in the middle, and originally the second part ended completely differently. The transparent helmets never broke—they stayed on to the end, but filled with new memories instead of old trauma. I was planning an ending where, over a shot of the two of them walking away hand in hand, the transparent helmets float above them, showing them imagining a life together even into old age. But while I was running prompts in Kling, it generated a clip where the two helmets shatter—something I never asked for. The

moment I saw it, I knew. The helmets breaking and coming off, rather than filling up—people smashing their own walls to truly see each other—was a far more honest ending, and that accidental cut is what taught me that.

6. What advice do you have for filmmakers hesitant to adopt AI?

AI is the brush, not the painting. If you're clear about what you want to say, AI becomes a powerful collaborator that makes possible the images you once gave up on for budget or manpower reasons. It's just as suited to work that builds meaning through small gestures and a restrained tone as it is to spectacle. Rather than fearing it, I'd suggest experimenting with one small scene first.

7. How did the music track influence your initial visual concepts?

My order of work is a little unusual. I've been composing for a while, so I had a number of unreleased songs sitting in my catalog. So rather than starting from the music, I wrote the synopsis first and then chose the song that best matched its emotion from what I already had. The track I landed on was "Multiverse" by Chlaenas, an artist on my label. I didn't use it as-is, though—I kept the melody and the feeling, but rewrote all the lyrics to fit the synopsis. That's how I shaped the music to support the atmosphere rather than compete with the image.

8. How are AI-dedicated festivals changing the indie film landscape?

I think they're opening a stage where creators can compete on idea and sensibility alone, in a space where budget and production scale used to be the barrier. What's interesting is that these festivals are starting to reward restraint and emotional coherence over work that simply shows off technology. The more AI lets us make anything, the more it matters to know what not

to make. Being able to push a personal, poetic voice all the way through on your own—that's the biggest change.

9. How do you balance making art for yourself versus making it for festivals?

Honestly, I try not to separate the two. When I make something with festivals in mind, my own voice tends to disappear. I make the film I genuinely want to see first, and find where it belongs afterward. "Just a Cup of Coffee" didn't begin as something to show anyone—it started from an emotion I needed to work through. I think that honesty—the idea that people aren't broken by dramatic conflict but by the quiet weight of what they carry unseen—is what ended up reaching the audience.

10. Who are the filmmakers or visual artists that inspire your work the most?

Damien Hirst. There happens to be an exhibition of his in Korea right now, and I went to see it in person. His work of suspending a shark in formaldehyde, preserved as if it were still alive, was strange and powerful. That tank—holding something dead as though it were living—actually became the direct motif for my transparent helmets. The idea of wearing a tank-like helmet, inside which dead memories of the past govern the judgments of the present, came from there. A single work of visual art posed a question that became the central image of the whole film.