Two years after being suddenly transported to another world, Rin Tachibana, a romance-challenged woman in her thirties, has built a quiet and stable life for herself as a clerk for the Magic Knights. Her peaceful routine is upended when she receives a secret directive from the king and the head of the Border Guard. They request that she perform a highly unconventional service for her arrogant colleague, the beautiful but notoriously misogynistic Magic Knight Oscar Garland. The reason given is medical his life is purportedly at risk if his pent-up magical power, which is linked to his libido, is not regularly released.

Despite her fierce refusal, Rin is reluctantly persuaded by the promise of anonymity and the official framing of the task as a necessary treatment. Disguised from head to toe in a black hooded cloak, she visits Oscar in a dark room. Her mission is to provide manual release, a duty that begins as a purely clinical chore. However, as she continues her secret nighttime visits, Rin finds herself fascinated by the sight of the proud and stoic knight losing control under her touch. What starts as reluctant duty becomes something she secretly looks forward to, as the thrill of power and Oscar’s increasingly desperate reactions awaken a surprising spark in her.

Rin must now juggle her normal daytime responsibilities alongside her secret after-hours activities. Her relationship with Oscar during work hours is contentious at best, as he remains cold and dismissive, unaware that the mysterious woman who serves him at night is the same clerk he ignores by day. The tension escalates as the lines between duty and desire blur. Oscar, who carries deep trauma from past experiences with women, begins to show an unexpectedly vulnerable and sensitive side exclusively to his nighttime partner, creating a stark contrast to his public persona. Meanwhile, Rin herself is emotionally guarded, having been hurt in past relationships back in Japan, leading her to convince herself that her growing feelings are merely part of the act.

As the story progresses through its major arcs, the central conflict evolves from a purely physical arrangement to an emotional entanglement. The first notable arc establishes the bizarre premise and Rin’s initial reluctance, showcasing her early attempts to maintain a professional distance while Oscar struggles with his conflicting feelings of hatred toward women and his physical need for Rin. A significant turning point occurs when Rin falls ill, revealing Oscar’s hidden concern for her as a person rather than just as a provider of relief. This leads to a period of mutual pining where both characters are painfully aware of their feelings but unable to confess due to the secretive and transactional nature of their relationship. A later arc involving a碑文調査 (inscription survey) mission forces them into close quarters outside the castle, where their daytime animosity gives way to genuine partnership and romantic tension. An incident with an aromatic flower that acts as an aphrodisac further complicates matters, pushing their physical relationship beyond its original boundaries. Ultimately, the narrative follows their journey from a secret contract of convenience to a public, loving union as they overcome their respective traumas and insecurities.