The Yanagisawa couple passionately desired a child, encouraging each other and diligently trying to conceive. However, after two, then three years passed, they remained childless and deeply troubled. One day, they decided to undergo medical tests, and the results revealed that their daughter-in-law, Chisaki, was infertile. The couple then turned to the husband's mother, Shiho, and asked her to become their surrogate mother.