Yuuto Akiyama, a butler in the Ijuuin household, dedicates himself to atoning for his father’s past misdeeds, approaching his duties with relentless optimism and a guileless trust in others. His unshakable composure persists even when faced with mortal dangers, such as discovering Serena Ijuuin’s vampiric nature and her intent to consume his soul. Miraculously surviving her attack, he becomes entangled with Serena and the household’s enigmatic members, unaware his resilience stems from a concealed heritage: he is the son of the Vampire King.

To protect Yuuto from his impending decline, the Vampire King concealed his heir with a loyal servant, burying the truth of his lineage. This heritage grants him immunity to vampiric harm and an enigmatic charm that draws supernatural women to him, sparking romantic pursuits from Serena and others. Yuuto navigates these advances passively, reacting to their intensity rather than reciprocating it.

As latent vampiric powers awaken—enhanced abilities befitting his royal blood—Yuuto uncovers his father’s misunderstood legacy, once branded treasonous in vampire society. These revelations redefine his bonds within the household, particularly with Serena, whose initial predatory intent shifts into attachment. Relationships with figures like the maid Mizuki and patriarch Retsudō Ijuuin further test his adaptability, challenging him to reconcile his human morals with his supernatural destiny.

His journey intertwines romantic complexities, familial truths, and the weight of royal expectations. Though his core optimism endures, each revelation strains his trust in others, forcing him to confront the blurred lines between loyalty and betrayal in a world of vampiric politics and hidden agendas.