Masuo Tooyama, known as Thomas, is an unemployed individual marked by social awkwardness and a lack of direction. His background as a "dull guy" without stable employment leads to a pivotal incident during a routine job search. On a crowded subway train, Thomas encounters Ayane Tachibana; her appearance and "refreshing smell" trigger intense arousal in him. Accidental physical contact occurs when Thomas's bag becomes stuck, resulting in him touching her hip. Though he retreats to avoid causing a scene, this moment awakens his repressed sexual impulses.

An elderly man witnesses the encounter and later approaches Thomas, offering instruction in "an ancient Chinese secret" concerning seduction and sexual techniques. This mentorship catalyzes Thomas's development. Under the old man's guidance, he acquires specialized knowledge focused on eliciting sexual pleasure in women, emphasizing methods applicable in public settings. Thomas evolves from a hesitant observer into an active practitioner.

Thomas's development centers on the systematic application of these acquired techniques. He transitions from unemployment and social ineptitude to actively seeking opportunities in crowded public spaces like trains and streets. His approach involves targeting encountered women, utilizing the taught methods to stimulate them sexually without their prior consent. This pattern of unsolicited acts defines his character arc as he grows increasingly confident and pervasive. The narrative confines Thomas's portrayal solely to this trajectory of acquiring and implementing these techniques across public encounters.