Kazuya, a son-in-law who lives with his wife and her parents, quit his job due to excessive stress and became unemployed. The harsh words of his father-in-law cut deep into Kazuya's heart... but in contrast, his mother-in-law Rui embraces Kazuya with Buddha-like kindness. Kazuya helps with the housework during the day, but what catches his eye are Rui's breasts, which are far too big! Kazuya quickly regains his lost vitality and energy, and his twisted desire for Rui's big breasts grows...