Tsuyoki ari(強き蟻)

Based on the novel "Tsuyoki Ari" by Seicho Matsumoto In her past, Isako Sawada ran a restaurant. She then met Nobuhiro who is 31 years older than her and an executive of a corporation. They eventually married. Nobuhiro owns a large mansion and his money is managed by housekeeper Saki Tsubaki. Isako Sawada doesn't like that arrangement, but she hides her contempt because she has a plan. Her plan is to become a widow in 3 years and inherit one billion yen from her husband. Isako Sawada schemes to have Nobuhiro die in an apparent natural manner and she is having a relationship with another man.