naka ushiro, akikawa yayoi (umamusume), umamusume, highres, 1girl, all fours, animal ears, ass, barefoot, blue eyes, blue one-piece swimsuit, competition school swimsuit, feet, from behind, horse ears, horse girl, horse tail, long hair, looking at viewer, looking back, multicolored hair, one-piece swimsuit, open mouth, orange hair, outdoors, ponytail, poolside, school swimsuit, smile, soles, solo, streaked hair, swimsuit, tail, toes, white hair