"I just wanted to protect her. That feeling wasn't a lie. Where did I go wrong?" Rejected by the one who meant more to him than anything, Subaru is still unable to recognize that he may have done something irreversible. He then finds out that some disturbing movement has been detected within Roswaal's domain, where Emilia and the others are. He's certain that he can save them somehow, so in spite of Rem and Crusch's opposition, Subaru makes his way back to Emilia...

Suddenly, high school student Subaru Natsuki has been summoned to another world on the way back from the convenience store. With the biggest crisis of his life being summoned to another world, and with no sign of the one who summoned him, things become even worse when he is attacked. But when he is saved by a mysterious, silver-haired girl with a fairy cat, Subaru cooperates with her to return the favor. When they finally manage to get a clue, Subaru and the girl are attacked and killed by someone. Subaru then awakens in the place he was summoned and notices he gained the ability "Returns by Death" and has become a helpless boy that only has the ability to rewind time by dying. Beyond the despair, can he save the girl from the fate of death?