Every thousand years, the zodiac is chosen anew. The old rule of a foot race has been replaced by a battle of happiness known as the Zodiac Royale. In this free-for-all, animal participants from various species compete to be among the next twelve signs of the zodiac. Each animal is bound by fate to a human master on Earth, and their ranking in the competition rises only when they successfully bring happiness to that master.

The story centers on Ichika Kotobuki, an ordinary high school girl with a secret passion for tokusatsu—flashy superhero shows with dramatic special effects. One day, she finds a wounded dog on the roadside and tries to help it. To her shock, the dog transforms into a humanoid figure named Komamaru. Komamaru is a contender in the Zodiac Royale, and by saving him, Ichika becomes his chosen master. Though initially reluctant to get involved, she agrees to participate on the condition that if they win, she will receive a full year of prosperity.

Komamaru knows that his only path to securing a zodiac spot is to make Ichika genuinely happy. Drawing inspiration from her love of tokusatsu, he decides to model his behavior after the noble, flashy heroes she admires. Together, they navigate the competition, facing other animal contestants and their human masters, all while Komamaru struggles to balance the over-the-top heroic persona with the quieter moments needed to truly brighten Ichika’s everyday life. The manga blends comedy, fantasy, and school-life elements as Ichika and Komamaru learn what it means to be partners and what happiness really costs in the race for the zodiac.