Fuyune, Akine, and Natsune. The three sisters love horse racing and racehorses, and a new racehorse is born on their farm. The horse is named "Shikio", and the three sisters dream of having him win the Japan Derby. Time passes, and Fuyune becomes a trainer. Akine became a ranch manager. And Natsune became a jockey, pursuing the dream she had entrusted to her beloved horse. However, Shikio, the most important of the three sisters, is still living a smoldering life as a "racehorse who has given up on winning."