Sarabure: Mesukousei no Uma Ikusei Nikki

Ever since she was a child, Sakura has loved horses more than anything! She enrolls in Narita Agricultural High School, which has a newly established department of horse breeding to raise thoroughbreds, and there she meets Satsuki. Along with Shion, whose grandfather is a horse owner, and Miyako, whose family runs a horse ranch in Kumamoto, Sakura runs through her youth in a land rich in nature.

(Source: Comic Walker, translated)