Ai, the daughter-in-law, is being urged by her mother-in-law to see her grandchild's face. One day, her mother-in-law suggested that we go on a trip to a hot spring. Ai is enthusiastic, but her mother-in-law orders her to have a baby in a hot spring, and even makes her drink Chinese herbal tea that is said to increase her sexual desire. On the day of her trip, the effects of herbal tea made Ai so excited that she couldn't be satisfied with sex with her husband. On the other hand, her father-in-law is also energetic and tries to hold her mother-in-law, but she refuses.