This concept is closer to "minimal light", not "glow in the dark" or "neon lights".
Initially wanted black on black with minimal light but I found the slight hue more aesthetically appealing, I also tried to eliminate white, creating a more dim environment.

I seem to have figured a lora setting suitable for me, right now tagging the dataset is the biggest issue, the result can't seem to work uniformly across all model. It's also weird this model have a wider weight range since I didn't change much setting.

What does it do?
[COLOR+STYLE] It generates DARK images with the shadows and minimal light. Depending on the model's base brightness, you may 1) generate character with black skin and/or 2) generate luminous backlighting.

What are the triggers?
This model does not need any trigger.
Strengthening prompts: Umbr4, Black, Dark.

Recommended Weight
Depending on the models used, the weight is good from 0.5 to 2.0.
On average, 0.8 to 1.3 have a more stable result.

Recommended model:
Some of the models that are closer to my initial ideas are: Breathe, Dark Sushi 2.5D, Crystal Cauldron, majicMIX horror, ReV Animated, RE:QUIEM, Store Bought Gyoza, WandaoMix
If you use models that have pastel or light color base, they will only create shadow towards purple hue and not be able to generate black/dark results.

Extra note:

This lora is good to generate cityscape (building, street, alley), night scene, plants & flowers and certain still life.
This lora also limits color to only Black, Turquoise, Cyan, Blue, Purple and Pink.
Maybe red and green too.

CORE Color Series:

• CMYK-CORE - Cyan, Magenta, Yellow, Black, White.

• PRIMARY-CORE - Red, Blue, Yellow, Black, White.

• SECONDARY-CORE - Orange, Green, Purple, Black, White.

• UMBRA-CORE - Black with dark glow.

Reflection: Tried a different way to tag my dataset, somehow I am able to generate the lora without trigger, not sure how I feel about it. Also surprisingly this lora have a widely strength.