Akari and her husband Ryuta are happily married and trying to conceive. However, after failing to get pregnant, a fertility test reveals that Ryuta has a low sperm count, making conception difficult. Around this time, Akari and Ryuta's father-in-law, Daigo, visits and discovers the medical report about Ryuta's condition. Driven by his strong desire to see a grandchild, Daigo decides to take over the pregnancy efforts in place of his son. While Ryuta is away, Daigo slips Akari an aphrodisiac, causing her to become intensely aroused. Overwhelmed by Daigo's skill, Akari orgasms repeatedly. Though initially confused and resistant, she gradually succumbs to the pleasure and begins to accept him.