Miwa Kanzaki (Wakana Matsumoto) is a stay-at-home housewife to her husband, Hiroki Kanzaki (Kei Tanaka), as the couple plans on having a child someday. However, their marriage is on the rocks: Miwa’s love for her husband has faded and he no longer treats her well, leaving her feeling trapped. One day, Miwa meets her childhood friend Ryo Fuyutsuki (Tatsuya Fukazawa), whom she hasn't seen in years but always loved. In a night that changes things forever, they sleep together – and Miwa later finds out that she is pregnant with his child. Fearing the prospects of divorce and single motherhood without financial stability, she decides to tell Hiroki that the baby is his, setting off a chain of events that will change all of their lives forever.