In the Yamoto Empire, a nation where humans and ayakashi coexist in an uneasy balance, spiritual power determines one’s place in society. Nanao Byakurenji, a kind-hearted girl born into a noble family, possesses an exceptionally high level of this power and was promised in marriage to Reito, the young lord of the Byakurenji main house. Her happy future is destroyed when her jealous cousin, Akemi, tricks her into leaving the protective barrier of the family estate. Nanao is attacked and kidnapped by an ayakashi, and though she is eventually rescued, she bears the mark of a demonic curse on her forehead, a spiritual seal that marks her as tainted.

The incident costs Nanao everything. Her engagement to Reito is broken off, and Akemi takes her place as his bride. Nanao is forced to wear a monkey mask to hide her cursed scar and lives as a mistreated outcast within her own family, enduring constant abuse and performing the lowest chores. For two years, her existence is one of isolation and hopelessness.

Her life changes forever when she meets Yako Benitsubaki, the young and willful head of the Benitsubaki clan, one of the five most powerful families guarding the empire. When Nanao’s mask is accidentally shattered, Yako sees her face and is immediately drawn not only to her hidden beauty but also to the great spiritual power that radiates from her. He offers her a way out, a new life as his bride.

Nanao accepts and leaves her torturous past behind, but she soon discovers that her new husband carries his own deep scars. Yako is known as a Tsubaki Demon, cursed by his own family lineage. To survive, he must ingest the blood of women with high spiritual power. Nanao, with her potent spiritual energy, becomes the perfect vessel for him. Despite this unsettling revelation, life in the Benitsubaki estate feels like a dream to Nanao. For the first time, she is treated with kindness by Yako, his supportive father Yaichirou, and their married shikigami, Zenki and Goki.

As Nanao adjusts to her new position, she begins to uncover the complexities of the world she has entered. She learns that her cursed scar might be more than just a mark of shame and that her own spiritual power is exceptionally rare and valuable. Her growing bond with Yako, who promises to one day kill the ayakashi that cursed her, deepens into genuine affection, even as she provides him with her blood to sustain his life.

Their fledgling happiness is threatened from multiple sides. Nanao’s past returns to haunt her when she encounters her ex-fiancé Reito, whose feelings are beginning to shift. Meanwhile, Yako’s mother, Tokiko, a woman of royal lineage who despises her son for his cursed constitution, sees Nanao as a threat and schemes against the couple. As tensions within the five noble families rise, Nanao must find the courage to stand on her own, master her latent abilities, and decide if her contract marriage can become a true union of love, all while navigating a world where political intrigue, ancient curses, and dangerous ayakashi threaten to tear them apart.