Yuji and Yukari have been married for several years, and their daily lives have settled into a calm routine. However, one night, Yuji receives a call from a friend who is having an affair, and he realizes that he has been cuckolded. This sparks an idea in him: to have another man sleep with his wife. He devises a plan to secretly administer an aphrodisiac to his wife, Yukari. Under the influence of the drug, Yukari's senses blur during a massage session at an esthetic salon, leading her into sexual intercourse with another man. The story unfolds through Yuji's conflicted emotions as he watches the act, and explores the complex inner feelings hidden within Yukari.