Ryōta Nonomiya is a successful businessman who is focused so much on work that he neglects his wife, Midori, and son, Keita. Upon his return home one day, Midori tells him that the hospital where Keita was born urgently needs to speak to them, and Ryōta senses trouble. After arriving at the hospital, the couple learns that their biological son Ryūsei was switched with Keita at birth, and after DNA tests prove the error, they must now make a life-changing decision to either keep Keita, the boy they raised as their own son, or exchange him for their biological son.