Reiko, who used to work as a model and then at a publishing house, lived with her husband while both working. However, her father-in-law, who lived with them, developed dementia, and she quit her job to take care of him. Then, her father-in-law praised Reiko, who still boasts a bewitching figure even though she has retired from active duty! Reiko, pleased, shows off her extreme swimsuit, but that strongly stimulates her father-in-law's dick! Reiko, who seems to have seen through her accumulated desires, involuntarily wets her crotch and allows even insertion with her father-in-law's intense torment... And in the meantime that her busy husband doesn't know, the two's affair escalates...