Before humans came to be, the world of Hinoaruchi was a skybound paradise ruled by various races of demi-beings, with the dragon clans of Ryujinkyo holding a place of honor under the protection of the dragon goddess Ryusui. However, a prophecy foretells a great change as the goddess's power begins to wane, and the first sign arrives during the Festival of Birthing Winds, when a most unusual child hatches from a dragon’s egg. This boy, named Kamuna, is born with the form of a soft-skinned human, possessing only a single scaled dragon arm and a small tail. Seen as a strange omen, he is both revered as the Child of God and feared as a potential herald of disaster in a society that has never seen a creature without fur or scales.

The story follows Kamuna as he grows up in the utopian but uneasy nation of Ryujinkyo, struggling with his identity as the first human in a world populated by demidragons, demiwolves, and other beast clans across eight distinct kingdoms. Determined to prove his worth, he begins training in the ancient martial art of ryuken, where his visible vulnerability masks a unique and growing strength. His efforts quickly fuel a fierce rivalry with Gindu, a powerful and aggressive demidragon who sees Kamuna as a weak anomaly that threatens the purity of their kind.

As Kamuna navigates his childhood and pushes against his limitations, a larger conflict brews beneath the surface. The divine pulse that sustains the land becomes a target for restless factions outside Ryujinkyo who seek to control its power. An elder dragon receives a vision from the dying goddess Ryusui, who reveals she is almost out of scales, suggesting that the age of demi-beings is ending and the age of humanity is beginning. This revelation forces Kamuna to confront his destiny; he stands as the bridge between two eras, and his existence forces the utopian society to question its own perfection, as cracks begin to show in the logical, god-governed rules of his world.