Since childhood, Saya has admired her caring older brother, Shou, who has always protected and prioritized her. Their close-knit bond flourished despite parental absence, fostering a tranquil life together. However, everything changes when Saya is bitten by a pure-blooded vampire, transforming her into one. Confined at home to prevent her from succumbing to her newfound instincts, Shou, a vampire hunter, vows to eradicate the vampire who turned his sister. Amidst his relentless quest, a complex dilemma unfolds as Saya's feelings intensify beyond sibling affection, challenging their relationship. As tensions rise, Shou faces a pivotal decision: yield to his sister's advances or eliminate the vampire threat. Can Shou save Saya from her vampiric fate, or will their forbidden romance alter their destinies irreversibly?