Meet Midori Makibao, a diminutive white racehorse with a unique appearance reminiscent of a donkey. Despite his unconventional looks, Makibao relies on his determination and swiftness to emerge victorious in prestigious racing events. Overcoming initial challenges due to his physical traits and other setbacks, Makibao embarks on a journey driven by his desire to outshine his arch-rival, the legendary Superhorse Cascade. Additionally, he is fueled by the heartfelt mission of reclaiming his mother, who was separated from him to settle a farm debt. Through a series of trials and races, Makibao faces numerous obstacles but ultimately rises to prominence as a remarkable and resilient racehorse.