Yui is a diligent and honest young wife who works at a local factory. Her husband, the factory manager, has awakened to his cuckold fetish, and she goes out drinking with a technical intern trainee. The intern, who has not been able to release his sexual desire, cannot control his desire for his wife, and he starts to tease her, which gradually escalates. Yui accepts it for her husband's sake, but gradually she can no longer resist the pleasure of his big dick.