Lilia Rainworth, originally from modern Japan, perished in a traffic accident before reincarnating into the otome game world of "Regalia of Saints, Demons and Maidens" as its intended protagonist. This rebirth elevated her status from commoner to nobility and secured her engagement to Crown Prince Cedric Jeanne Ellmeyer.

She possesses light skin, violet eyes, and exceptionally long rose-colored hair flowing past her hips. Her hairstyle typically features two locks tied with pink ribbons and bangs ending just above her eyes. Her standard attire is a white blouse adorned with a rose decoration at the collar paired with a hopbush-colored skirt, though she sometimes wears her academy's blue uniform.

Outwardly, Lilia projects kindness, compassion, and innocence, aligning perfectly with her destined role as the "Holy Sword Maiden." Her true personality, however, is manipulative and delusional. She perceives this world solely through the lens of her past gaming experience, viewing all other characters as non-player characters (NPCs) devoid of genuine personhood and capable of respawning. This belief leads her to orchestrate schemes without regard for real-world consequences, such as inciting Selena Gilbert to unleash demonic incense during a school festival or fabricating threatening letters against herself. She finds entertainment in creating narrative challenges, particularly for Aileen d'Autriche, whom she recognizes as a fellow reincarnated individual. Lilia considers conventional happy endings tedious and actively disrupts storylines to foster unpredictability, describing her actions as akin to "bashing action figures together."

Her key abilities include an exceptional memory for intricate details of the "Regalia" game series and its sequels, which she leverages strategically. She excels in political manipulation, employing feminine charm and indirect persuasion to influence nobles and orchestrate plots while avoiding direct culpability. Though initially unskilled in combat, she later masters wielding the Sacred Sword, eventually fighting alongside Aileen in confrontations. Her tactics involve exploiting other characters' predefined game roles, such as manipulating Cedric's insecurities or influencing Selena as the protagonist of the game's sequel.

Lilia consistently antagonizes Aileen and Claude Jeanne Elmeier, the demon lord. She engineers crises like the demon incense attack at Mische Academy, justifying her actions by asserting no real harm occurs in a fabricated world. When confronted by Aileen, she openly admits her manipulations but evades accountability due to lack of evidence. Her motivations blend a desire for narrative excitement with a warped sense of mentorship, claiming to "foster" subsequent game heroines for greater strength. This persistent meddling establishes her as a recurring adversary who thrives on chaos and narrative subversion.