Narita Taishin

A small-statured, but strong-hearted and audacious horse girl. Her attitude towards trainers is more than just hostile, she vocally rejects them outright, and considers all of them annoying and strict. She seems like a cold, sarcastic kid, but she hides an earnest, burning passion for running in her heart. Though you might not guess it because of her slight physique, she can explode with speed in the last stretch of a race, and is feared as "Demon Leg Taishin."

(Source: MyWaifuList)