Melphiera Marchalrayd, an earl's daughter, grapples with social rejection among the nobility for her unconventional passion: preparing and consuming monster meat. Rumors branding her the "Voracious Villainess" arise from her determined quest to transform this reviled ingredient into refined cuisine, defying the kingdom's deep-seated prejudice.

Her late mother struggled with "overflowing magic," a condition that exposed Melphiera early to unusual practices, though specific maternal ties beyond this remain undefined. Facing pressure from her step-mother to secure a marriage or be confined to a cloister, Melphiera reluctantly attends social events seeking a match while hiding her culinary pursuits.

A pivotal moment occurs during a monster attack at a noble gathering, where she encounters Aristide Roger de Galbraith, the feared "Blood-Mad Duke." Unlike others, he shows genuine fascination with her expertise in monster-based cuisine. Their mutual interest in monsters—his through hunting, hers through gastronomy—ignites an immediate connection. Their relationship swiftly evolves into courtship, culminating in Aristide's engagement proposal. He actively champions her passion, gifting rare monsters like a gold-fleeced royal moodle for her culinary experiments.

Relocating to Galbraith territory, Melphiera attempts to integrate monster meat into the knights' travel rations, striving for wider acceptance of her cuisine. Simultaneously, she uncovers parallels between Aristide's battle with "overflowing magic" and her mother's history, driving her research into preventing his descent into "blood madness." Her efforts expand to exploring safe consumption methods for magic-afflicted monsters, intertwining her culinary mission with his survival in a land overrun by monsters since the Calamity.