Sarasvati, alias Saras, commands authority as a vampire ninja leader, overseeing subordinates like Seraphim within her clan. She conceals her true nature under the human pseudonym Kirara Hoshikawa. Embracing the stage name Lovely Kirara, she thrives as a popular net idol, captivating fans with a dominant, provocative performance style starkly contrasting her ninja origins. This dual life remains hidden from most, including her subordinates.

Her striking appearance features long black hair with blunt bangs and piercing crimson eyes. Sarasvati typically dons a simple school uniform for daily life, occasionally switching to casual attire: a sleeveless cardigan over a frilled white tank top secured with a black ribbon, a red skirt, and boots. Her idol persona showcases Gothic flair: a white sleeveless polo shirt beneath a black frilled corset, a waist belt, black boots, decorative vampire wings, and a dark overcoat draped loosely to emphasize her shoulders.

Sarasvati blends stern leadership with underlying kindness. She rigorously enforces vampire ninja traditions, displaying impatience and aggression towards deviations—like Seraphim's failure to eliminate Eucliwood Hellscythe, which led Sarasvati to brand Seraphim a traitor and order her death. Yet, she later rescues Seraphim and others from threats such as the King of the Night, revealing protective instincts. Despite her seriousness, she challenges clan norms by pursuing an idol career. Her stage persona exhibits sadistic tendencies, while her compassion surfaces in actions like permitting Yuki Yoshida to attend social events.

A significant development is her obsessive romantic fixation on Ayumu Aikawa, sparked by a fetishistic attraction to his buttocks observed during a school tournament. This fuels persistent stalking and open declarations where she addresses him as "My Dirty Darling." She engineers encounters, inviting him to concerts and orchestrating an indirect kiss she interprets as marriage under vampire ninja customs. She prepares a marriage certificate for them, its validity ambiguous. Her feelings endure despite other romantic interests in Ayumu's life.

Within the series plot, Sarasvati initially targets Eucliwood for attracting Megalos, assigning Seraphim the assassination. After revoking the contract following the sealing of the Underworld gates, she gains prominence in later arcs. She manages a café where Ayumu participates in challenges and increasingly integrates into his social circle. Sarasvati defends Ayumu and his allies during conflicts, notably aiding them against the King of the Night during Eucliwood's disappearance. She participates in school life and public events as both Kirara Hoshikawa and Lovely Kirara.

Her abilities encompass standard vampire ninja techniques: teleportation, swordsmanship, and martial arts. She specializes in water manipulation, forming combat blades and employing water defensively. Additional skills include violin playing, linked to her past in the ninja village orchestra.

Key relationships define her arc. With Ayumu, interactions shift from formal to obsessive romance. She maintains a senpai-kōhai dynamic with Seraphim, delivering items and guidance despite conflicts over traditions. With Yuki Yoshida, she shares mutual respect and camaraderie. Her backstory hints at undisclosed leadership origins within her clan. By the light novel's conclusion, she restarts high school as a student, continuing her complex relationship with Ayumu.