Chisato Shoda felt deep guilt toward her daughter, who had grown up in a single-parent household due to her own infidelity. After her daughter married, Chisato became firmly determined to protect her daughter's family at all costs. However, she received an unexpected request from her son-in-law—he suspected her daughter of having an affair. To save her daughter from the brink of divorce, Chisato decided to perform a blowjob on her son-in-law, taking her daughter's place. This act was both an atonement for her past sins and an indirect way to preserve her daughter's marriage.