Sachiko Nagasawa (Mukai), 40 years old, lives with her kind husband Tatsuro and obedient son Yuta. An ordinary and frugal, but warm and friendly home. However, Tatsuro and Sawako have one big secret. What she has been hiding from her son, Yuta for a long time, is revealed by chance. A small family about to crumble. In Yuta's wounded heart, a serious decision sprouts...