Luminous Valentine from That Time I Got Reincarnated as a Slime / Tensei shitara Slime Datta Ken
Keep in mind that settings may vary slightly between different versions. See below for more details.
When I tested this with different checkpoints and LoRAs, it seemed to work quite well.
Pony:
A LoRA weight of 0.8 works great, though you can adjust the strength as you prefer.
Prompts I usually used:
long hair, grey hair, heterochromia, red eye, blue eye, black dress, short dress, white collar, black hair ribbon, black hairband, black arm guards, short sleeves,SD 1.5:
A LoRA weight of 0.7 works great, though you can adjust the strength as you prefer.
Prompts I usually used:
long hair, grey hair, (heterochromia), red eye and blue eye, black skirt, white collar, hair ribbon, black arm guards, short sleeves