At the age of 10, Shin Tamura’s happy family life was torn apart when his policeman father was sentenced to death and imprisoned for murder. Now, some 30 years later, Shin is determined to prove his father’s innocence by solving the mystery at the heart of the case. Finding himself transported back in time, Shin must uncover the shocking truth, change the past, and restore his family’s happiness.

Shin timeslips back to 1989 and becomes a teacher at the primary school where the murders for which his father was arrested occurred. He decides to try to change his father’s fate by helping him to prevent the incident from happening. But then, Shin’s older sister, Suzu, disappears.

Shin has a notebook detailing everything that will transpire in the future. But he can’t let anyone know his father will be convicted of murder. To save his family, Shin struggles with whether to tell them the awful truth. Then the true murderer foreshadows another crime. Who will his next victim be?

Shin timeslips from 1989 to discover his life in 2020 has gotten even worse. His father is still in prison, and his mother and older brother are dead. And his older sister Suzu changed her name and married someone who is deeply involved in the murder. To save his family, Shin comes up with a new plan…

Shin has returned to the present to find that everything has changed, including the fact that Yuki is no longer his wife. Now a reporter for a weekly magazine who is writing about the case, Yuki puts him in touch with a new witness who offers Shin a glimmer of hope that he might yet be able to clear his father’s name.

The one witness who can prove Shin’s father’s innocence is killed by Satsuki. So did Satsuki commit the murder Shin’s father is accused of? But then someone tries to poison Satsuki too! Next, Shin receives an invitation to meet the true murderer and decides he must accept it, even if his own life is in danger.