Jun Megami works as a gravure model, but one day she is invited to an esthetic salon advertising a "sensory development program." Though initially suspicious of the name, her curiosity about the treatment overpowers her hesitation, and she decides to go through with it despite her anxiety. Inside, she is handed a mysterious questionnaire, filling it out amid growing embarrassment and unease before the session begins. The oil massage starts, coating her entire body in slippery warmth, stimulating her highly sensitive skin. The therapist then applies oil directly to her breasts and genitals, intensifying the stimulation to extreme levels, advancing her sensory development. The pleasure gradually builds, clouding Jun's mind and eroding her rationality. Soon, she finds herself actively craving the next stage of the program. Writhing in intense pleasure, her body convulsing with each sensation, the erotic drainage program escalates further and further. Jun surpasses her limits, drawn deeper and deeper into overwhelming ecstasy.