In a world where nearly ninety percent of the population naturally produces umarekawari unkon, a sentient and talking poop, the most popular national sport is Keiun, a high-speed race where a rider mounts their own living feces to compete for glory. The story follows Hikata, a young boy who dreams of becoming a professional Keiun jockey. He faces a humiliating and isolating problem: he is the only student in his class who has never produced a partner unkon. Despite his daily efforts, nothing comes out, and he is on the verge of giving up on what seems like an impossible dream.

Just as the boy sheds tears of frustration, he experiences a sudden and intense stomach ache. From this struggle, a magnificent, golden unkon is finally born. This special creature, possessing a brilliant shine and a confident personality, introduces itself as Unko-Oh. He declares to Hikata, I kept you waiting, and just like that, the duo is formed. Unko-Oh is not just a piece of excrement; he is a proud steed with incredible latent speed, determined to carry Hikata towards his ambitions.

The series chronicles Hikata and Unko-Ohs journey through the competitive world of Keiun. The setting includes the racing circuits and schools where riders and their unkon train together, forming unique bonds between human and feces. In this world, unkon are treated as friends and family members, possessing distinct personalities and the ability to speak. The narrative blends the tropes of a热血 sport manga with absurdist comedy, delivering serious racing action alongside its outrageous premise.

One of the notable narrative arcs follows the protagonists time at a Keiun school, culminating in a graduation race with professional dreams at stake. As the race reaches its climax, a massive explosion near the goal throws the rankings into chaos. This event reveals deeper conspiracies, uncovering the past and secrets of a formidable rival named Negao, the strongest man in the sport. The story explores broken promises, surprising masterminds, and races that are never as straightforward as they seem, all leading to an unpredictable conclusion for Hikata and his friends.