Not much love is given to flat chest characters of Brown Dust 2 on this site, so I got to train one myself. Without prior knowledge, I think I got a good one in like 4 tries. 5th try suppose to be better, but the style got shifted probably due to using too many generated images in training over original images. So I'll just stick with this version for now.
It is quite difficult to get consistent identical character of official setting out of this one, due to she having: heterochromia, mismatched legwears, pattern on the collar, color pattern of flower wreath and white stripe blue ribbon with white end. Some of those features will get wrong for this lora, and I gave up on the ribbon thing. Character wise, the style is good enough. If you don't mind getting messed up combinations of features mentioned above, then this lora is fine.

Trigger words:

Character only:
Refithea_BD, 1girl, flat chest, long lilac hair, red and blue eyes, heterochromia, +_+, pointy ears, thick eyebrows

Main costume:
Refithea_BD, Refinthea_main, 1girl, flat chest, long lilac hair, red and blue eyes, heterochromia, yellow dress, red and blue pantyhose, +_+, pointy ears, mismatched legwear, twintails, thick eyebrows

Optional: yellow high heels

Wedding costume:

Refithea_BD, Refinthea_wedding, 1girl, flat chest, long lilac hair, red and blue eyes, heterochromia, flower wreath, white wedding dress, white pantyhose, long white gloves, +_+, pointy ears, thick eyebrows

Optional: bouquet, white high heels

Swimsuit:

Refithea_BD, Refinthea_sukumizu, 1girl, flat chest, long lilac hair, red and blue eyes, heterochromia, white sailor collar, school swimsuit, +_+, pointy ears, azure blue ribbon with white stripes, hair ribbon, azure blue hair band, twintails, thick eyebrows

Optional: blue lifebuoy, water gun, blue sandals

stuffed_animal can be added if you want to include Glutti (will become strange animal if lora strength is low); remove thick eyebrows if you dislike it.