In a world where only dogs and cats exist, centuries of strife have defined the relationship between the two species. The dogs, who are highly social and organized, won a devastating continental war and established a kingdom called Ise on the only major landmass. The cats, more independent and unruly, were driven out to the vast sea that now covers most of the planet. From these waters, they survive by forming pirate crews and repeatedly raiding the dogs.

The protagonist is Jean, a young dog born at sea under unusual circumstances. He lives with his mother Rosa and his adoptive father Azul, a small cat who raised him. The family moves constantly between small islands, and Jean dreams of one day finding a safe, permanent home where the three of them can live together happily, free from hunger, storms, and the endless conflict. This dream is shattered when pirates attack their island. Azul sacrifices himself to protect Jean and Rosa, and Jean is knocked into the sea.

Jean washes ashore on a strange island and is rescued by King Zahav, a massive and powerful lion pirate. Zahav reveals that Jean has been chosen by the Urgia, one of three great treasures that serves as a key to awaken something important. Zahav’s goal is to find the legendary lost supercontinent of Si Land, which lies somewhere beneath the ocean. He believes that discovering this new continent with its abundant resources could end the perpetual war between dogs and cats and create a peaceful world. Jean joins Zahav’s crew, hoping to rescue his mother, who was likely captured rather than killed because she is a rare Langha breed capable of producing valuable animal fibers.

The narrative follows Jean, a dog who has learned to move with the agility of a cat thanks to his upbringing, as he navigates the violent clash between canine kingdoms and feline pirates. His journey is tied to the search for Si Land and the mysteries of the Urgia, while the broader world remains locked in a bitter conflict rooted in ancient hatred and survival.