Every time you die, you go back to a specific time in the past like the checkpoints in a game. It may seem cool at first but doing the same thing over and over again will make you feel exhausted. Jacob Rothschild is a regressor. Every time he dies he goes back to the past and starts over. The story here tells the experiences he goes through to figure out the mysteries behind his abnormal ability and to find a way to set himself free from the endless regressions.