Even in her second year of high school, the aristocratic young lady Suu has zero friends. An extreme loner, she dreams only of experiencing the ordinary, uneventful youth that has so far eluded her. One day, a beautiful young man named Yuki appears before her. He is mysterious and claims to have lost his memory, and he quickly becomes the first friend Suu has ever made. But nothing is as simple as it seems. Yuki’s true identity is that of a bodyguard assigned to protect Suu, a fact that upends her quiet world. The story follows their forbidden master-servant love, branded as a zero-distance dangerous romance. Despite being told that romance is forbidden, Yuki takes the motto to heart in his own way, pushing the boundaries of their relationship with unpredictable actions that leave Suu constantly flustered.

As the story unfolds, Yuki helps Suu experience all the classic school-life scenarios she has always longed for — studying together in the library, sneaking into the pool after school, and building friendships. Her classmate Kuga also begins to take an interest in her, creating a love triangle. A school trip forces all three into the same group, sparking tension and jealousy. During summer vacation, Kuga discovers the secret between Suu and Yuki, further complicating matters. On a group cruise, Kuga’s growing feelings for Suu trigger Yuki’s possessive instincts. At the cultural festival, Suu is confessed to by Kuga and, prompted by his words, begins to recognize her own romantic feelings for Yuki. But when she tries to get closer to him, Yuki inexplicably rejects her.

A mysterious young man named Hotaru then appears, someone who knows Yuki’s past. This sets off a wave of dramatic conflict. Hotaru’s violent confrontation with Suu forces Yuki to intervene, and Suu’s father ultimately steps in to resolve the crisis, allowing Yuki to return to her side. After a period of separation, Yuki and Suu reunite, and Yuki finally asks her directly if her confession of love was real, bringing the story to its emotional conclusion.