Recently, I think I've watched K-pop Demon Hunters about 30 times at home because of my kids. Then I suddenly started imagining who Rumi's mom and dad were, and why her dad became an evil spirit. So I tried to create a story with AI, but one thought led to another, and I ended up creating an unnecessarily high-quality work that includes English writing, voice acting features, actual Sunlight Sisters music, images, and interactive viewing on a web platform. Through intense labor and even burnout, I kept asking myself: What did I do? Why did I do it? These questions arose, but answers were hard to find. I created something truly useless, with genuine passion, at genuinely high quality. Above all, writing fanfiction for the first time at this age..
1. Creating the Story: Teaching KDH to AI
I wanted to create this story with AI. But AI naturally knew nothing about K-pop Demon Hunters—it's a 2025 work, and AI was trained on data up to 2024. It felt like briefing a new team member on the entire company history.
I first enabled the internet search function and asked it to fetch the entire KDH story. I created a Claude Project and gradually built up knowledge there. In the first session, AI grasped the basic storyline of KDH, but something was missing. It felt like trying to understand a drama just by reading Wikipedia.
Creating a prequel required more than just KDH's main story. I gathered stories about Celine's shamanic background, Jinwoo's past, Mira and Joy's relationship, Lion Voice's identity, and most importantly, the hidden stories of Rumi's parents and added them to the project.
I collected fan theories created by fans worldwide through Gemini Deep Research. I gathered theories from Reddit's r/KpopDemonHunters, Twitter's #KDHTheories, and even Chinese Weibo fan theories. There were creative theories like 'Rumi's father is actually a time traveler,' 'Mi-young's grandmother is the real final boss,' and 'Rumi's curse marks are actually an ancient Korean map.'
I set the story in the familiar 1990s—the era of S.E.S. and Seo Taiji and Boys. Director Maggie Kang of K-pop Demon Hunters had already mentioned that S.E.S. was the motif for Sunlight Sisters (SLS). Rumi's father as Seo Taiji? It might sound childish in Korea, but for global readers unfamiliar with Seo Taiji, it could be an intriguing story worth exploring. Besides, Seo Taiji has been most associated with 'demonic' themes in Korean music history—though of course it was all misunderstanding and controversy. Plus, there's actually a connection to Seo Taiji, and I included LA as an important setting that global readers can relate to.
Using Claude Opus 4.1, I created the first version. An epic saga spanning 10 chapters emerged. Chapter 1 alone exceeded 15,000 words. I got tired just reading the first two chapters.
2. Vibe Coding the Story: Writing Like a Developer
So I created a project using Claude Code that could process text quickly and simultaneously with a large context size. I made each chapter a separate React component and built a centralized character database.
I commanded Claude Code like doing code review and debugging:
- •'Find all inconsistencies in this entire text' → Found 23 consistency issues
- •'Make the characters clearer' → Systematized each character's personality and motivation
- •'Make each character's weapon consistently Korean traditional weapons throughout all chapters' → Mi-young's sword became a Jeju female diver's knife, Celine's weapon became a shaman crescent blade, Stacy got twin glass-manipulating batons
What stood out was when I said 'Make Gwima consistently male throughout.' Claude Code reported that 31 modifications were needed across 7 files and completed all corrections in 10 minutes. It would have taken at least 2-3 hours if done manually.
3. Adding Images: Enhancing Visual Appeal
The condensed text was interesting, but the webpage felt empty without images. So I asked Claude Code to create Midjourney prompts suitable for each chapter. I also utilized some images that briefly appeared in the original K-pop Demon Hunters.
For example, Chapter 3's prompt: 'Korean Liberation Day 1995, Gwanghwamun Square, massive colonial building exploding, three young Korean-American women in modern clothes holding glowing weapons, supernatural golden light streaming from building, cinematic lighting, film noir style --ar 3:4 --v 6'
The results from Midjourney were satisfactory. After 4-5 attempts per image, I obtained suitable covers.
4. Adding Audio Features: The Birth of AI Voice Actors
The novel had grown to over 50,000 words, and I was getting tired of reading it all. I thought it would be nice if AI could read it to me, so I integrated OpenAI's TTS API. Initially, I just fed the entire text at once, resulting in a 20-minute monotonous audiobook.
When I told Claude Code 'I wish the voice would change for each character,' it created a JSON script that divided text by sentence, including dialogue, voice, character, and emotional direction. However, as the text kept changing and I debugged by listening, I regenerated it about 8 times. Running it as a script took about 20 minutes each time.
I cast 7 different AI voices:
- •Mi-young: shimmer (warm and emotional)
- •Celine: coral (traditional and mysterious)
- •Stacy: nova (bright and energetic)
- •Jimin: onyx (deep and mature)
- •Gwima: ash (threatening and dark)
- •Narrator: alloy (neutral and clear)
By switching voices throughout, it became less awkward and more immersive and natural.
5. Music Composition: Collaborating with Suno AI
The story needed fitting background music. I asked Claude Code to plan lyrics and musical styles, specifically requesting concrete lyrics and melody directions for Jimin's final song 'Forever Love' and Mi-young's 'Dreams Come True.'
Claude Code created prompts:
- •Forever Love: 'Emotional K-pop ballad, male vocal, piano and strings, Korean lyrics about eternal love and sacrifice, melancholic yet uplifting, 1990s style'
- •Dreams Come True: 'Upbeat K-pop anthem, female group vocal, synthesizers and drums, Korean lyrics about hope and determination, bright and energetic, late 1990s style'
To select one song on Suno AI, I averaged about 8 attempts per song. I tried multiple times to find versions where lyrics, melody, and vocal style all satisfied me. Most were awkward or too modern, but a few really captured the 1990s K-pop sensibility.
The finally selected songs greatly enhanced the story's emotional depth. Particularly 'Dreams Come True' was perfect for expressing Mi-young's character who never loses hope.
6. Refining the Story: The Most Arduous Process
The most time-consuming task was reading through the story myself and refining it. AI's first draft was grammatically perfect but lacked emotional depth. My working speed was truly the bottleneck.
I would make small adjustments, feed them to AI, read again, and repeat. Memorable revisions included:
- •'Make Gwima consistently male throughout' → 31 corrections across 7 files
- •'Change Incheon to Kimpo Airport (1995 historical accuracy)' → Chapter 3 updates
- •'Remove Beverly Hills parking lot battle references (non-existent scene)' → Multiple chapter fixes
- •'Change 'One Last Song' to 'Forever Love' and update audio URLs' → Audio integration work
- •'Correct Jimin's retirement from Feb 5, 1997 to Jan 31, 1996' → Timeline consistency
Every revision was tracked with git commits. The commit messages reveal the development process:
'refactor: Update K-pop Demon Hunters story consistency and pronunciation'
'fix: Update K-pop Demon Hunters story consistency and build issues'
'feat: Create single source of truth for chapter data and add Stacy humor'
Eventually, I created chapterData.js, a centralized data file that resolved all inconsistencies.
7. Becoming a Director: 20,000% Efficiency
After multiple revisions, it achieved considerable completeness. An interactive web novel with 7 chapters, 45,000 words, 9 illustrations, and 4 hours of voice acting was completed.
Then reality hit. For about 5 days, I spent almost all my after-work time on this 'work.' Investing 6-7 hours daily, totaling about 30 hours? Though AI did everything, the intensity of mental labor was enough to cause burnout.
I intended to write a simple story but ended up directing and producing an interactive web novel. I probably wrote less than 5% of the actual sentences. Instead, I played the 'director' role: presenting ideas, designing structure, reviewing consistency, managing quality, and incorporating feedback.
But directing turned out to be much more exhausting than expected. While AI handled all the work, orchestrating everything and performing the director's role was equally draining.
Every night until dawn, I sat reviewing AI's output, giving revision instructions, checking overall consistency, coordinating character relationships, and managing story flow. While AI handled the actual creative labor, the mental fatigue of coordinating and making decisions was entirely mine to bear.
Ultimately, even in the AI era, the hardest tasks remain 'deciding what to create,' 'designing how to create it,' and 'managing quality.' Despite technological advancement, the essential difficulties of creation still seem to be humanity's burden to shoulder.
Why 20,000% efficiency? I couldn't have done this alone even with 200 times more time. Writing, illustration, voice acting, music composition, web development—hardly anyone can do all of this single-handedly. Even if possible, it would have taken years.
8. Cost and Efficiency: A $100K Project for $275
Actual Cost (AI-powered)
- Claude Max: $200
- OpenAI TTS: $14
- Midjourney: $10
- Suno AI: $10
- Total: ~$244
Traditional Approach Estimated Cost
- Writer: 3 months × $4,000 = $12,000
- Illustrator: 9 pieces × $500 = $4,500
- Voice actors (7): 4 hours × $200 × 7 = $5,600
- Web developer: 2 months × $5,000 = $10,000
- Project manager: 3 months × $6,000 = $18,000
- Total estimated cost: ~$50,100
In reality, it would have cost more. Considering staff scheduling coordination, management, music and recording studio costs, revision work, communication costs, and project delays, it could easily have reached $100,000.
9. Future Thoughts: Democratization of Creation
Working on this side project made me realize we're entering a strange new world.
While I couldn't create videos yet, in a year, I'll probably be able to turn this story into video format too. AI video generation tools like Google Veo3 and Runway are rapidly advancing.
Many jobs that would have existed for this work have disappeared. But if I had to work with those people, I probably wouldn't have started this project. Would I hire voice actors, music directors, illustrators, and web developers for $100,000 just to write fanfiction as a hobby?
AI definitely enables work that was previously impossible. It exponentially expands individual creative capacity and seems likely to raise the average quality of creative works overall.
But simultaneously, I had slightly scary thoughts. My easily created work might look similar to readers compared to something a real writer struggled with for months. It seems like a time to reconsider the value and meaning of creation.
10. Conclusion: A Tiny Glimpse of the Future
This 5-day experience meant more than just a simple side project. Jobs will definitely decrease due to AI. But AI will also enable countless things that were previously only imagined but never executed. More dreams will be realized, and more industries will emerge.
Perhaps in 2 years, anyone will be able to create their own movies, games, or novels. A world where creative barriers completely disappear. These past 5 evenings were a tiny glimpse of that future.
And right now, somewhere in the world, someone is creating their own story with AI. It's a fascinating and promising future.