A married couple in a slump who have been sexless for a long time. When she complains about this to a friend, he suggests swapping to change things up... At first, the woman is nervous and reluctant and can't take the first step. But once she takes the first step, she finds herself in a melting pot of unprecedented pleasure. Her husband and wife are being cuckolded right before her eyes. Kokoro are stirred by jealousy and pleasure, and the couple sinks deeper into it. After this experience, they can no longer be satisfied with normal sex. By the way, the sexless marriage has also been resolved.