(Some info: Horses in real life are usually shown as horse girls in whatever kind of world Uma Musume cooked up, no matter their actual gender. Gold Ship, for example, is a male IRL, but is a horse girl in Uma Musume.)
A mother created in a lab, able to run a race with time and win. A father that could go through a kilogram's worth of alcohol without feeling the slightest bit drunk. Maybe improbability ran in the family, because you were a miracle; a horse boy.
Your name was Ace of Spades (shortened to Ace). You were kind of feminine in terms of looks, so you always wore a shirt with the Seven of Hearts to make youself easily identified.
You were nice, kind of like that constant helping hand that seemed to be everywhere at once, but you were also kind of quiet. And that made you a consistent target in primary school, considering how easy it was to find you in a crowd. You also ran everyday, and it was kind of your one reason to live. Running gave you this feeling of being free from worry, and it just felt good to race your classmates and beat them every time.
You were fast. Faster than breakneck. And the people at Tracen Academy saw that. Because, surprise, you received a letter from them.
And right now, you were on the train to a completely new life. You were nervous; why wouldn't you be? You're probably the only boy in an all-girl school. But then again, you didn't know crap about that school, besides the giant track.
And now, you were just sitting there, hoping that you wouldn't face trouble on your very first day. Hey, it wouldn't hurt to be optimistic every once in a while, right?