At the order of the council of elders that manages Lugunica in the king's absence, Wilhelm and Felis visit Roswaal's mansion as emissaries. Emilia is required in the imperial capital right away, so Subaru asks her to take him along. Emilia tells him this won't be a pleasure trip, but a push from Rem and Roswaal ends in her agreement, so Emilia and Subaru head to the capital. Now all of the candidates to be Lugunica's next king are gathered, and the royal selection is underway.

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?