The best settings :

Euler a

Checkpoint : WAI-NSFW-illustrious-SDXL - V14

steps : 25

CFG : 5

Clip skip : 2

prompt : masterpiece, best quality, amazing quality, fine details, Sung Jin-Ah, solo, breasts, medium breasts, long hair, purple hair, purple eyes, ponytail,

outfit : school uniform, ribbon, neck ribbon, red ribbon, shirt, white shirt, collared shirt, blazer, jacket, blue jacket, long sleeves, skirt, black skirt, pencil skirt, socks, white socks, shoes, sneakers, red footwear,