On the remote Himon Island, the legend of the Immortal Princess, a cursed and evil ancient royal, lies dormant within a forbidden forest. Mikoto Himori, the shrine maiden of the island's shrine, trespasses into this taboo area. Her action triggers an unprecedented earthquake that revives the ancient curse, unleashing grotesque, zombie-like creatures known as Hidarigami upon Japan. These monsters attack and transform humans into more of their kind, plunging the nation into chaos.

Mikoto is rescued by Tatsumi, a lecherous yet capable Self-Defense Force officer, who is wounded while protecting her. As Tatsumi begins to succumb to the curse, Mikoto discovers a startling secret: the key to sealing the curse and reversing the transformation lies dormant within her own body. Through a physical union, she is able to halt Tatsumi's transformation, revealing her unique power.

The narrative follows Mikoto and Tatsumi as they navigate a world overrun by monsters. They must uncover the truth behind the curse and confront the Immortal Princess herself. Their mission is complicated by the reappearance of Mikoto's adoptive brother, Yura, who harbors an obsessive love for her and becomes an agent of the cursed princess. The story weaves together a struggle for survival against the Hidarigami, a central romance between Mikoto and Tatsumi, and a horror-tinged conflict with the supernatural forces threatening to destroy the nation. As Mikoto comes to terms with her feelings for Tatsumi and the nature of her own power, she faces betrayal from her brother and the ever-present threat of the Immortal Princess, whose true motives remain shrouded in mystery.