Mayu, who landed a job at a major trading company, finds herself assigned to the adult toy development department—an unfortunate twist of fate. Meetings are filled with an atmosphere bordering on sexual harassment, and though Mayu worries about her job performance, she realizes the male employees grow increasingly interested whenever she reveals her true feelings. Soon, they begin openly touching her underwear. Surprised by her own reactions, Mayu continues testing prototypes, earning high marks when her performance leads to a hit masturbator product. The next vibrator prototype becomes a runaway success as well, making Mayu realize she has a natural aptitude for this work. Under the pretext of collecting a junior male colleague's semen sample for research, Mayu dives deeper into increasingly explicit testing sessions.