1girl, alternate costume, animal ears, between breasts, black hair, blush, breasts, cleavage, frown, full body, halloween costume, hat, holding, holding syringe, horse ears, horse girl, horse tail, long hair, looking at viewer, mejiro dober (umamusume), nurse, nurse cap, simple background, solo, syringe, tail, thighhighs, umamusume, white background, white eyes (20220506white)