Kazu is one of Satoru's primary school classmates.

Satoru Fujinuma is a 29 year old manga artist struggling to make a name for himself following his debut. But, that was not the only thing in his life that Satoru was feeling frustrated about… He has a unique supernatural ability of being forced to prevent deaths and catastrophes by being sent back in time before the incident occurred, repeating time until the accident is prevented. One day, he gets involved in an accident that has him framed as a murderer. Desperate to save the victim, he sends himself back in time only to find himself as a grade-schooler one month before fellow classmate Kayo Hinazuki went missing. Satoru now embarks on a new quest: to save Kayo and solve the mystery behind her disappearance.


Twenty-nine-year-old Satoru Fujinuma is floundering through life. Amid his daily drudgery, he finds himself in the grip of an incredible, inexplicable, and uncontrollable phenomenon that rewinds time, a condition that seems to only make his drab life worse. But then, one day, everything changes. A terrible incident forever changes Satoru's life as he knows it...and with it, comes a "Revival" that sends Satoru eighteen years into the past!
 
In the body of his boyhood self, Satoru encounters sights he never imagined he would see again--the smile of his mother, alive and well, his old friends, and Kayo Hinazuki, the girl who was kidnapped and murdered when he was a boy the first time around. To return to the present and prevent the tragedy that brought him back to his childhood in the first place, Satoru begins plotting a way to change Hinazuki's fate...But up against the clock and a faceless evil, does eleven-year-old Satoru even stand a chance?
 
(Source: Yen Press)
 
Note: Was nominated for the 18th Tezuka Osamu Cultural Prize Reader Award in 2014 and for the 7th, 8th and 9th Manga Taisho Award between 2014 and 2016. Also nominated for the 40th Kodansha Manga Awards in 2016.
 
Volume 9 contains the 5-chapter “Boku Dake ga Inai Machi:Re” side story.