AI x Creative RTA Part 1: Solidifying Character/World Settings and Theme Songs in 10 Days [2026.03 Latest Version / Krita AI Diffusion / Gemini / ChatGPT / Suno]

Hello. For the Generative AI Exhibition Vol. 05 and the 2nd Female Otaku Generative AI-only event, I intended to make a "How-to Book for My AI Creation Method." However, the creative world I made as a sample hit my personal preferences so perfectly that I could no longer focus on making a how-to book. Instead of creating a guide, I will carefully reveal the whole process in this note article series, "AI x Creative RTA." I hope this making-of article provides some helpful hints.

What You Need

Image Generation AI

Used for character design gacha. Since it is a time when it is difficult to get a gaming PC, please use whatever you like, such as Nijijourney.

In this article, I am using Krita AI Diffusion. The model is SDXL, the checkpoint is Conceptor, and for LoRA, I use my own style LoRA trained on 35 hand-drawn pictures, as well as some charm-like LoRAs that influence quality and detail.

Please refer to the article below for the basic usage of Krita AI Diffusion.

LLM

In this article, I used Gemini 3.1 Pro and ChatGPT 5.4 Thinking. I have paid subscriptions for both.

Markdown Editor

Great for saving character design prompts and conversation history.
I recommend Obsidian or Joplin. Anything that can sync content between your smartphone and PC and export to Markdown-formatted text files is fine.

Suno

The well-known music generation AI. I have a paid Pro plan for this.

Basic Premise: Be Honest About Your Preferences in Your Creations

This creation started from the desire for a collection of the lowest yet highest "preferences":

The explosive motivation and drive you feel when making things you love become a major engine for completing a work. Be honest about your preferences.
If you don't know what attributes you like, try noting down the "things you feel are lacking in the many works you enjoy." If you shape those missing parts in your own creation, you are guaranteed to be happy at the very least.
If you don't know what attributes you like, try noting down the "things you feel are lacking in the many works you enjoy." If you shape those missing parts in your own creation, you are guaranteed to be happy at the very least.

Let's Do Character Design Gacha with Prompts Packed with Fetishes

Once you have decided on the "preferences" you want to pack in, write them out in a prompt and have the image generation AI output character designs. Try generating a few times; sometimes the weird combinations the AI makes or the way it fills in parts you didn't instruct it to will strike a chord with you. Do not hesitate to adopt those elements.

In my case, I tentatively decided on the genre as "a transformation hero story where school uniforms are business wear, and they transform from school uniforms into tight suits to fight," and asked it to propose character designs. (The reason the world-building of the genre is crazy from the start is because I really wanted to include the setting of "people who are not students wearing school uniforms.")
First, Hero No. 1 (tentative) became as follows for After Transformation / Before Transformation.

I will also post the prompts. Fan art is welcome, so please feel free to use them.

1man, (mature male: 0.8), sharp gaze, pink hair, tsurime, shoulder length hair, medium hair, black cybersuit, nsfw, explicit, model sheet, bags under eyes, tall, (slim: 1.2), messy hair, cross bangs, (head gear), white background, (white face: 1.3), (white makeup: 1.3), (black eyeshadow: 1.3), (gakuran: 0.7), gold buttons, long white scarf, cowboy shot,

1man, (mature male: 0.8), sharp gaze, black hair, tsurime, shoulder length hair, medium hair, nsfw, explicit, model sheet, bags under eyes, tall, (slim: 1.2), messy hair, crossed bangs, white background, (gakuran: 1), gold buttons, cowboy shot, glasses,

Let's turn Gemini into a 'limit-break otaku' to help us brainstorm.

It's hard to find someone to brainstorm creative ideas with, isn't it?
But don't worry! Gemini is excellent at that kind of creative brainstorming.
To make it easier to get ideas suggested during brainstorming, let's turn Gemini into a 'limit-break otaku'!

今、{ジャンル}の創作を作ることを考えています。設定を書きますので、限界オタクになって可能な限り長文で妄想してください。

LLMs often have issues with sycophancy and hallucinations, but since I am looking for creative writing generation this time, I will proceed with the brainstorming conversation while accepting sycophancy and hallucinations. Of course, please check and correct any proper nouns or points that seem suspicious or incorrect yourself.
I talked about wanting to add characters and expand into manga or games, and the brainstorming reached 400,000 characters.

Saving conversation content as a text file is important

Even with Gemini's 1 million token context window, if you brainstorm in the same chat for a long time, it will suddenly forget the content of the earlier conversation. (Since turning it into a 'limit-break otaku' generates many ideas, there is a lot of token waste.)
Once the conversation has gone back and forth for a while, copy and paste the content into an editor. Then, you can keep only the idea-generation parts, or rewrite and organize the parts you don't like. Once you have organized it to some extent by hand, save it in Markdown format.

Let's have ChatGPT organize the brainstorming history with Gemini

It's popular to use 'ChatGPT 5.4 Thinking' to 'write a fictional 2ch-style thread.' I will apply that to my own creative work. I will attach the Markdown memo I organized earlier, have it read the file, and have it write a long anonymous bulletin board thread.

You can cool down the creative passion you were building up with Gemini to simulate 'what kind of things might be said about it,' or expand on the daily life of the main characters from the perspective of mob characters.

Never run out of ideas! The 'Heinrich's Law Prompt'

Even if you brainstorm with Gemini or have ChatGPT organize it, there are times when you just can't think of certain situations. I will introduce a powerful prompt for those times.

Pass the following prompt to ChatGPT.

// {}内は適宜書きたい作品のシチュエーションに差し替えてください
{治安の悪い町でローカルヒーロー活動をしていると}遭遇しうるイベントや出来事を思いつく限り羅列してください。それは再現性のないものでも良いです。

As a result of passing this to ChatGPT 5.4 Thinking, it listed 150 events, ranging from things that might happen daily to dramatic events.
Let's ask Gemini one by one how the main characters would think and act regarding the situations obtained from these results! The resolution of your world-building will increase significantly!

As a side note, the key to this prompt is the 'Please list as many events and occurrences that could be encountered as possible. They don't have to be reproducible.' part. This is based on the concepts of 'near-misses' and 'Heinrich's Law'.

By applying this law to creative work, the AI can take many situations into account.

Making theme songs with Suno in your spare time boosts your mood.

If you have time, creating theme songs (character songs) for each character with Suno makes the creative process even more fun. I use Suno's automatic lyric generation feature (the Legacy Lyric model performs better). To get the lyrics for the songs below, I threw the following prompt at it quite casually.

不眠症の変身ヒーローの歌。羊を数えるように敵を数えながら撃ち、「おやすみなさい」でトドメを刺す

Thinking about a logo boosts your mood even more.

If you are someone who can design a logo yourself, it will boost your mood even more if you also think about a title logo, using the image style proposed by NanoBanana as a reference. I made mine in Affinity. Please give it a try!

Conclusion — To my past self who wanted to create but had no subject matter to draw.

Two years later, I have finally solidified the concept for a creative project about 'supporting a fictional visual-kei techno band.' At the first female otaku generative AI-only event, I was very happy that many participants talked about this subject and requested to 'read a detailed making-of.' I decided to respond to that request, and as a result of exploring the optimal solution for the division of labor between humans and AI using the latest AI combinations, I wrote this article as the 2026.03 latest version. It was exhilarating to build the 'characters' and 'worldview' that form the foundation of creation at lightning speed together with AI.
I have successfully fallen into the swamp of new creation, but I am happy. Please rest assured that I will not stop the 'fictional visual-kei techno band' that I unveiled at the previous event.
If you have ever thought, 'I want to draw manga!' or 'I want to make a game!' but 'I have no ideas...', I would be happy if there is something here you can take away!

Next Episode Preview

Next time! AI x Creative RTA is...?
Since I want to turn this work into a game,I will use Antigravity and Godot Engine to build the rough framework of the game through Vibe Coding. Stay tuned!

This note is a place where a practitioner who can draw by hand and loves AI calmly leaves behind the making-of processes for illustrations, manga, videos, and more. It would encourage me if you could click the heart mark below!