In an adult commuter-student role-play, Hiyori is confused by an unfamiliar pleasure rising deep inside her on the usual train to school—something even her boyfriend has never given her. She desperately suppresses her moans despite hating the molestation, unable to accept that only the persistent fingers of a greasy middle-aged groper can draw out this ecstasy. After discovering that forbidden bodily pleasure, the once reserved and serious woman becomes addicted to his technique and eventually starts seeking out the molester herself to explore its depths.