While his wife was pregnant and returned home, Kazuya was struggling with unfamiliar household chores. - However, he struggles in vain and his house becomes a mess. - At that time, my wife's older sister, Yuri, barged in to help with the housework. - Kazuya is confused but happy about the sudden visit. - However, Yuri's real purpose was to relieve her pent-up frustration with her sister's husband. - Kazuya, unaware of this, takes a bath completely relieved. - Then Yuri walks in with a mysterious smile on her face...