Desparaia reigns as the supreme leader of the Nightmare organization and the primary antagonist of the series. She relentlessly pursues the Dream Collet, a magical artifact capable of granting any wish, seeking eternal youth and immortality. She believes achieving this will allow her to plunge the entire world into despair, a goal born from her profound fear of aging and vulnerability.

Her presence initially remains shrouded in mystery. She directs operations from a concealed office within Nightmare headquarters, communicating primarily through monitors or via her loyal secretary, Kawarino—the sole subordinate permitted direct audience. Her early appearance features a traditional Japanese-inspired aesthetic: a voluminous purple dress, a red cape, and a distinctive white mask completely obscuring her face, adorned with red lines and purple lips. Her brown hair is elaborately styled with golden hair ornaments.

Upon acquiring and using the Dream Collet near the series' conclusion, she undergoes a physical transformation. The mask shatters, revealing the face of a mature woman. Her attire shifts to a more ornate purple kimono-style outfit featuring lighter sleeves decorated with gold beads, a red ribbon belt, and multiple necklaces—one bearing a small mask. Her hair becomes more voluminous and loose, adorned with blue stones, a stone crown featuring a red gem on her forehead, and gold-beaded strands. Despite attaining eternal youth and beauty, this transformation brings her no internal peace or happiness.

Her personality is characterized by coldness, cruelty, and an unyielding pursuit of her goals through any means, instilling significant fear in her subordinates. Beneath this exterior lies profound loneliness and a subtle sensitivity to the loss of her followers, particularly Kawarino. Terror of aging and weakness fundamentally drives her actions, leading her to believe spreading despair offers the only path to solace.

Desparaia wields immense power. She generates countless shadow clones for attacks and manipulates emotions, exploiting vulnerabilities to instill despair and facilitate brainwashing. Her mere aura possesses enough force to repel powerful adversaries. Her overwhelming abilities are consistently portrayed as having the potential to consume entire worlds in despair.

Her relationship with Kawarino proves pivotal. He functions as her sole trusted confidant and intermediary, conveying her orders to other Nightmare members and reporting directly to her. His unwavering loyalty persists until the final confrontation. She initially dismisses the Pretty Cure team as mere obstacles to obtaining the Dream Collet. However, their persistent hope, embodied especially by Cure Dream (Nozomi Yumehara), gradually unsettles her and challenges her worldview.

Her story culminates in significant internal conflict and eventual redemption. After achieving immortality but finding no fulfillment, she confronts the Pretty Cures directly. Cure Dream recognizes shared humanity within Desparaia and reaches out, speaking of the universality of fear and the strength found in friendship. This sparks a nascent desire within Desparaia to understand hope.

When Kawarino, clinging to despair, attempts to interfere, she rejects his loyalty, inadvertently causing his demise. Overwhelmed by grief, loneliness, and the realization of her actions, she loses control of her powers. This triggers the catastrophic collapse of the Nightmare dimension, threatening wider destruction. Accepting responsibility, she proposes sealing herself within the collapsing dimension alongside the Nightmare headquarters to contain the devastation. She returns the depleted Dream Collet to Coco and Natts, explicitly apologizes to them, and willingly accepts her fate. The Pretty Cures, respecting her choice, seal the dimension, resulting in her implied demise alongside the crumbling realm.

Her name derives from the words "despair" and "pariah." She holds the distinction of being the first female main antagonist and final boss within the Pretty Cure franchise. Her character achieves a form of redemption through self-sacrifice, a resolution uncommon among major villains in the series. Her silhouette appears alongside other major villains in the film *Pretty Cure All Stars DX3*, representing the Nightmare organization; she does not appear in other All Stars films like *Minna de Utau♪ Kiseki no Mahou!*.