Dominura is a central figure among the Sibylla, the young priestesses who pilot the flying vessels known as Simoun. She is distinguished by her maturity and enigmatic past, serving as the oldest and arguably the most experienced member of Chor Tempest, the elite squadron to which she is assigned. While her body appears to be that of a nineteen-year-old, her origins are far from ordinary, as she hails from a different world or time, making her true age considerably greater and her aging process unique. This otherworldly origin is a key to understanding her detached perspective and the profound secrets she carries.

Dominura's personality is characterized by a calm, collected, and charismatic demeanor. She possesses significant commanding ability and often acts as a strategist, sometimes directing the battlefield in place of the official leader. She maintains connections with high-ranking officials within the Simulacran government, suggesting a history of political involvement that adds a layer of mystery to her actions. Despite her competence, she can appear emotionally guarded and pragmatic, a shell that slowly cracks as the series progresses. Underneath her composed exterior is a deep well of trauma, primarily stemming from being the sole survivor of Chor Dextra, a choir that was annihilated while attempting to perform the forbidden and powerful Emerald Ri Maajon.

Her primary motivation shifts dramatically over the course of the story. Initially, she is driven by a mission to uncover the secrets of the Simoun and the Emerald Ri Maajon, a pursuit that leads her to convince the engineer Waporif to commit the sacrilegious act of disassembling a Simoun's helix motor. What she witnesses inside the machinery shatters her, revealing devastating truths about her own role in history and the nature of the war. This mental breakdown leaves her in despair until she is saved by the young Sibylla, Limone. From that point forward, her motivation condenses into a singular, intense focus: her relationship with Limone. She decides to live and fly solely for Limones sake, dedicating her very existence to her young partner.

Dominuras most significant relationship is with Limone. She takes an interest in the prodigy and becomes her flying partner, acting as both a mentor and a source of emotional support. Their bond evolves from a maternal or instructive dynamic into a deeply romantic partnership. Dominura is fiercely protective of Limone, physically holding her close when others try to separate them, and she acknowledges that their mutual choice of one another is what allows them to achieve great power. It is in Limones presence that Dominura shows vulnerability, even shedding tears when hearing that she is needed. Their connection culminates in their successful performance of the Emerald Ri Maajon, which transports them through time.

Her role in the story is that of a tragic catalyst and a keeper of forbidden knowledge. As the last survivor of Chor Dextra, she is responsible for the forbidden technique that becomes a central point of conflict. Through her actions, she inadvertently becomes the reason for the war, and her journey is one of atonement. In a striking paradox, when she and Limone travel to the past after drawing the Emerald Ri Maajon, they become the legendary founders of the Simoun civilization. They are revered as the sacred Sibylla who appeared from the sky and taught the people the secrets of the Simoun, thus becoming the very origin of the society they came from. This creates a time loop where Dominura is both the student trying to learn the truth and the ancient god who created it.

Dominura undergoes a profound transformation from a mysterious political operative to a broken individual, and finally to a woman who finds purpose in love. Her development is marked by a descent into despair upon learning the cyclical nature of her existence, followed by a rebirth through Limones affection. However, this choice comes at a cost. Because she never goes to the spring to permanently choose a sex, her body begins to decay, and she exhibits the same sparkling, deteriorating condition as the ancient priestess Onashia, heavily implying she is destined to become that very figure. In the end, despite her failing body, she decides not to surrender but to embark on a new journey with Limone to explore other skies and timelines.

As a Sibylla, Dominuras notable abilities extend beyond raw piloting talent. She is a highly skilled strategist with considerable charisma and leadership qualities. Her true power lies in her experience and her knowledge of the Emerald Ri Maajon, a technique that bends time and space. Notably, she is the one who performs this forbidden Ri Maajon with Limone, and it is revealed that only by focusing her intention entirely on Limone can she successfully execute it. Ultimately, her greatest ability is her resilience and her capacity to forge a new destiny through an intimate bond, even when faced with the seemingly inescapable consequences of her actions.