Selnia Iori Flameheart, a scion of the prestigious English Flameheart lineage, navigates the elite corridors of Hakureiryō Academy as an upper-ed student flanked by servant-ed peers. Her identity orbits around aristocratic pride, manifesting in haughty poise and rigid adherence to noble traditions. Clashes with Akiharu Hino, a servant-ed classmate, ignite early hostility after his accidental breach of her personal space and relentless teasing of her ornate blonde hairstyle—twisted into whirling drills that hum with mechanical whirrs when agitated, earning her the contentious nickname “Drill.”

Academic prowess and familial expectations weigh heavily on Selnia, juxtaposed against a simmering discontent with upper-ed monotony. This restlessness finds purpose in her rivalry with Tomomi Saikyō, a childhood companion turned cunning rival. Their bond, once rooted in camaraderie, fractures into cutthroat competition fueled by Tomomi’s manipulative flair and Selnia’s envy of her social finesse and scholastic superiority. Beneath her assured exterior linger insecurities over Tomomi’s perceived advantages, stoking Selnia’s relentless drive to outshine her.

Interactions with Akiharu gradually thaw from frosty disdain to a charged interplay of barbed exchanges and unspoken care. She chastises his breaches of decorum yet betrays protectiveness during peril, epitomizing tsundere contradictions—a prickly shell shielding vulnerable emotions. Romantic stirrings toward Akiharu remain stifled by pride and her duel with Tomomi, who likewise covets his attention.

Introspective flashes pierce Selnia’s resolve, revisiting fractured memories of her past kinship with Tomomi and dawning awareness of her own heart. Subtle shifts—covert glances at Akiharu, exasperation at his obliviousness—hint at thawing rigidity, though her regal facade endures. The mechanized reactions of her drills, syncing with emotional turbulence, mirror inner turmoil, weaving levity with layered character nuance through the series’ comedic and romantic tensions.