Having saved up enough money, Yusaku Mukai is finally thinking about making a down payment on his first home. Nearby, Akemi gets ready for the night's dinner and prepares an evening drink. Close at hand is their daughter, Ayaka, who has been going to piano lessons. In this way, the Mukai family is a strictly ordinary family, the kind found anywhere. All three of them feel certain that their happy days as a family are bound to continue. One day while out on a business trip, Yusaku mistakenly receives a message on his phone. It should have been nothing more than a mistake -- an e-mail sent to the wrong recipient. But that message changes his life forever.