Desert Devil is a shadowy entity of shifting sand, created to serve Dark Precure. Its core purpose is harvesting Heart Flowers, the manifestations of human hearts, achieved by preying upon human despair, sadness, doubt, and fear. Initially a featureless silhouette composed of sand, it seeks targets overwhelmed by negative emotions.

To fully manifest and act within the human world, Desert Devil requires a human host. It approaches vulnerable individuals, exploiting weaknesses or offering false promises to gain consent for possession. Once possessed, the host physically transforms, merging with the sand entity into a monstrous Desertrian. This fusion amplifies the host's negativity, suppresses their consciousness, and turns them into a tool for stealing Heart Flowers.

Desert Devil manipulates sand, conjuring storms, erecting barriers, and forming weapons. Its power level and specific abilities fluctuate based on the emotional state and traits of its current host. Defeating a Desertrian requires the Cure team to purify the negative energy, separating the host and causing the sand entity to dissipate or be recalled.

A significant evolution occurs during Desert Devil's possession of the antagonist Sasorina. This unique, profound merger creates the powerful Desert Devil Sasorina. In this state, the entity gains greater autonomy, a distinct personality, and significantly enhanced power. It exhibits arrogance, sadism, and fierce loyalty to Dark Precure, actively strategizing and engaging the Cures directly. This form represents the pinnacle of Desert Devil's manifested power and agency within the primary narrative. The character embodies despair, corrupting humans to steal Heart Flowers, with its possession of Sasorina marking its most developed and autonomous state.