Tatsuya experiences the worst day of his life: the game that he developed tanks on its sales; his girlfriend breaks up with him (just when he was about to propose to her); and finally, that night, when he was speeding up with his car, he gets into a big accident.

But instead of dying, he finds himself surrounded by a bright light and wakes up to find himself in his room. He quickly realizes he has somehow gone back to the time he was a child while retaining all his memories and knowledge from the future. He decides to take this second chance given to him to make his life better…