Black dragon rider Sana and her companions are determined to cross the Skywall, a sacred aerial domain also known as the upper divine realm, in order to confront and defeat their sworn enemy, the White Dragon. The journey is not simply a matter of will, however, as reaching that altitude presents profound physiological and environmental challenges that no ordinary human or dragon has fully overcome. After a traumatic incident leaves Sana unable to fly, her quest becomes both a personal struggle and a scientific mystery. Believing that the key to surviving the Skywall lies in understanding the physical differences between humans and dragons, Sana infiltrates a monster research institute to study dragon anatomy. There, she and her party make a critical discovery: dragons possess an internal organ capable of generating breathable air, a finding that could enable human survival in the sky's upper reaches. This breakthrough draws the attention of the kingdom's knight order, which seeks to collaborate, though not everyone is eager. Former two-wing unit member Vince harbors private misgivings about the escalating mission. When Sana's group finally breaches the Skywall, the triumph is short-lived. The White Dragon appears without warning, forcing them into a desperate battle. Despite careful preparation and a well-laid strategy, the fight quickly spirals beyond what they anticipated, testing the limits of their resolve, their dragon bonds, and the very discoveries that brought them there.