1girl, ahoge, animal_ears, bikini, black_hair, breasts, character_doll, cleavage, collarbone, ear_ornament, hair_ornament, halloween, horse_ears, horse_girl, horse_tail, kitasan_black_(umamusume), kouzuki_hajime, looking_at_viewer, medium_breasts, medium_hair, navel, open_mouth, satono_diamond_(umamusume), solo, swimsuit, tail, umamusume