The story begins with the protagonist, a 25-year-old man living a rather unfulfilling life, who unexpectedly hires a "home security guard." This guard turns out to be a friend he's known online for five years, named Rena, whose true identity and gender he was unaware of. Rena, who claims to be a "curvy JK beautiful girl," has impulsively run away from home in Sapporo to Tokyo and sought refuge with the protagonist. This decision stems from a conflict with her parents over her future and her desire for a "dynamic escape."
The protagonist's life is characterized by a mundane job, a lack of social connections, and a reliance on anime and the internet for entertainment. His only real social outlet is his weekly visit to a bar owned by his childhood friend, Gami. Gami, who has undergone a physical transformation from male to female, serves as a confidant and a source of comfort. It is during one of these Friday visits that Rena contacts the protagonist with her request for a place to stay.
Rena's arrival is dramatic. She appears at the protagonist's local station, a "curvy JK beautiful girl" with a red carry bag, as she described. The protagonist, initially skeptical and believing it to be a prank orchestrated by Rena, is shocked to discover that she is indeed a high school girl and the same person he's known online. He brings her back to his "horror house," a notoriously haunted property he rents cheaply due to its dark history.
Upon arriving at the protagonist's home, Rena is overwhelmed by the "altar" he has set up in his living room as a sign of respect for the house's history. Despite her initial shock and overwhelming shyness, Rena quickly adapts. The protagonist, realizing the difficulty of face-to-face communication with Rena's severe social anxiety and stutter, suggests they communicate via computer. Through rapid typing, Rena reveals her true identity as a high school student and her desire for "reality escape." She had planned to use her "curvy JK beautiful girl" persona to solicit "instant relationships" online to fund her stay, but her plans are disrupted by the protagonist's refusal to engage in such activities.
Rena's family situation is revealed to be complex. Her parents are distant, her sister attends the University of Tokyo, and she feels misunderstood and pressured by her family's expectations. Her impulsive runaway act was a desperate attempt to escape this pressure. The protagonist, despite his own shortcomings and tendency to avoid responsibility, decides to let Rena stay, effectively hiring her as a "home security guard."
Over the course of a year, Rena transforms the protagonist's life. She becomes an exceptionally skilled housekeeper, taking over all domestic duties and even improving his cooking and personal grooming. This leads to a significant improvement in the protagonist's own lifestyle and work performance, even resulting in a salary increase. He becomes dependent on Rena's presence, and neither of them addresses the precariousness of her situation as a runaway minor living with an unrelated adult. Their relationship remains one of "senpai" and "kouhai," with Rena maintaining her "curvy JK beautiful girl" persona online while acting as a capable domestic helper in reality. The narrative concludes with the protagonist and Gami reflecting on the past year, acknowledging the protagonist's passive approach to the situation and Rena's continued, albeit problematic, presence in his life.
