The narrative picks up with Sakimori Reito returning to his ancestral home after five years of intensive training in America. The Sakimori family are renowned bodyguards, tasked with protecting important figures. Reito, despite his lineage, was sent away by his grandmother at age ten to a special training facility, where he learned various combat skills from a former soldier, including survival, firearms, knife handling, and hand-to-hand combat. He finds his family's old, ivy-covered mansion unchanged.
Upon entering, Reito is confronted by his uncle, a man with foreign features and a condescending demeanor. His uncle reminds Reito that he was sent away as a nuisance and that the family's leadership will go to his own son, not Reito, who he dismisses as a mere "dog." Reito, however, reiterates his lack of ambition for the family headship.
Reito then meets his grandmother, the matriarch of the Sakimori family. She acknowledges his growth and recalls Reito's arrival five years prior, after his parents' death. Reito explains his difficult childhood in an orphanage, where he was ostracized and bullied, leading him to seek refuge with his paternal family. His grandmother reminds him of the condition she set for him to stay: he needed to acquire sufficient skills for the bodyguard profession. Reito has now passed her rigorous five-year training program, a feat usually taking over a decade.
His grandmother then presents him with his first assignment: to protect Charlotte L. Jay Wilford, the illegitimate daughter of the British Prime Minister. Charlotte is described as a foreign-looking girl with blonde hair and blue eyes, who is extremely misandrist. To overcome this obstacle, Reito is instructed by his grandmother to disguise himself as a girl and attend Charlotte's school as a female bodyguard. Reito is taken aback by this unexpected and embarrassing directive, especially considering the high stakes of the mission, which involves significant rewards and strengthening ties with Britain.
The scene then shifts to Charlotte's high school. During lunchtime, a handsome student named Takao Zaitsu, the son of the Minister of Finance, attempts to confess his love to Charlotte with a bouquet of roses. Charlotte, however, reacts with extreme disgust and verbally abuses him, calling him "disgusting" and "dirty." She slaps him forcefully, sending him and the roses to the ground. The surrounding students are unfazed, noting that this is the 120th person to be rejected by Charlotte, reinforcing her reputation as the "Ice Princess" due to a past trauma that made her intensely dislike men.
Reito wakes up in his room at the Sakimori residence, the harsh training of the American facility a stark contrast to the peaceful Japanese environment. Despite the safety, he maintains his combat readiness, keeping a knife and pistol hidden. He reflects on his master's advice about the vulnerability of sleep and the dangers faced by men in positions of power, especially when accompanied by women. Reito admits he has no room for romantic feelings, as his primary focus is on avenging his parents. He is deeply reluctant about his upcoming assignment, which requires him to cross-dress and attend a prestigious academy filled with the children of various dignitaries, where bodyguards are commonplace. He worries about the negative impact this unusual debut will have on his reputation as a bodyguard.
