Xu Zong transmigrates by accident to Tracen Academy, where he becomes Spica's trainer and activates a Diary System.
As long as he writes a training diary every day, he can earn rewards. But Xu Zong never expected his diary to be read by Special Week, Narita Brian, Duramente, Tokai Teio, Kitasan Black... and many others.
Mejiro McQueen: "Wait, when the diary says 'chubby horse,' it's not talking about me, is it? How am I chubby?"
Tokai Teio: "Why does everyone know I like drinking honey?"
Narita Brian: "Who's a crybaby? I... Even if I win, I definitely won't cry. Probably!"
Nice Nature: "Why do you call me a bronze medal collector? Waaaaah, Trainer, you're so mean."
Kitasan Black: "What's a support card? Watch out for the big hammer? And who is this big hammer?!"
Satono Diamond: "Huh? Why does everyone call me Brother Diamond?"
Special Week: "Who's 'Specially Dumb'? Wait, do I have a little sister?"
Agnes Tachyon: "Are real racehorses alternate-world counterparts?"
Xu Zong's diary is full of all kinds of strange things, and the Uma Musume eagerly await each new entry. As its contents grow, the Uma Musume learn more and more about their alternate-world counterparts.
