Touka is an omega who has never experienced a natural heat and cannot bear children, a condition that has earned him the scornful label of withered flower. He works at an omega brothel where the owner orders him to find an alpha willing to take him, even if he has to use deception. One night, after being forced to take a heat inducer and sent out to find a partner, Touka collapses in the streets and is found by Zeit, a wealthy alpha merchant from a foreign country. Zeit listens to Touka's situation with unexpected kindness and abruptly proposes, asking Touka to become his mate.

Touka, moved by the offer and longing for a better life, accepts. He soon learns the truth behind Zeit's proposal. Zeit is the second son of a powerful merchant family and has been placed in a succession contest with his older brother by their father. The brother, once close to Zeit, has become hostile and suspicious. Zeit has no desire to inherit the family business, so he chooses Touka as a mate precisely because Touka cannot have children. By taking an omega who cannot produce heirs, Zeit hopes to prove to his brother that he has no ambition to claim the family legacy. The marriage is a calculated arrangement from the start.

Despite the pain of discovering Zeit's deception, Touka resolves to make the best of the situation. He earnestly declares that he still wants to be happy with Zeit and works to earn his genuine affection, even within a transactional relationship. Zeit's attitude is initially cool and practical; he sees the bond as a convenient solution to his family problems and treats the relationship as a formality. He even marks Touka's neck, the traditional act of claiming a mate, before any romantic feelings exist between them.

As they begin living together in Zeit's mansion, tensions with Zeit's brother escalate. The brother, still paranoid about the succession, grows increasingly hostile. Meanwhile, Touka unexpectedly goes into heat, something considered impossible for a withered flower. Zeit rushes to care for him, and the proximity and pheromones draw them physically closer. Their physical intimacy deepens, and Zeit slowly starts to develop genuine feelings for Touka, drawn in by Touka's steadfast devotion and gentle nature.

The conflict with Zeit's brother reaches a crisis point when the brother has Touka kidnapped. Zeit must confront his family head-on to rescue him. This event forces Zeit to recognize how much Touka truly means to him, transforming the fake bond into a real one. In the final arc, Touka becomes pregnant with Zeit's child, despite everyone having believed he could never conceive. The pregnancy throws Touka into turmoil because he remembers that Zeit chose him for his infertility, and he fears that Zeit might no longer want him now that he is capable of having children. Touka tries to flee the mansion in panic, but Zeit stops him and affirms his love, making it clear that his feelings are no longer conditional.

The story concludes with Touka accepting the pregnancy and Zeit fully embracing his role as a devoted partner. A post-arc epilogue shows the two of them raising their son together as a family, with Touka finally receiving the genuine love and security he always wanted. The setting is a world with three secondary genders where alphas can only bond with one omega for life, a principle that makes Zeit's initial willingness to form a casual, convenient bond a significant reflection of his emotional detachment at the start. The narrative follows Touka's journey from a devalued outcast to a cherished mate, and Zeit's evolution from a self-serving pragmatist to a man capable of deep, unconditional love.