Despite medical advancements revealing that elderly men's sexual desires don't diminish but actually intensify, the four grandfathers of the Honma household prove no exception. This family has a long-standing tradition of favoring large breasts, and their criteria for choosing brides has always been strictly based on bust size. As a result, Yuri, the wife of the current head of the household, Dontaro Honma, not only meets this standard but is widely regarded as the largest-breasted bride in the family's history. Currently, with no care facilities available, the four grandfathers are stuck on a nursing home waiting list. Seizing the perfect opportunity during Dontaro's business trip, they all move into the Honma residence. What follows is the emergence of an entirely new, unexpected dynamic within the household.