1girl, alternate_costume, animal_ears, blurry, blurry_background, breasts, brown_eyes, covering_breasts, covering_privates, horse_ears, horse_girl, horse_tail, looking_at_viewer, medium_breasts, medium_hair, miyama_mizuki_(hoshihoshi1220), naked_towel, navel, nice_nature_(umamusume), night, onsen, red_eyes, sitting, solo, steam, tail, towel, umamusume