Natsuki Subaru is summoned to a parallel world on his way home from the convenience store. He's entranced at first by the fantasy world suddenly stretching before his eyes, but the cute girl he believes summoned him is nowhere to be found, and soon enough he's utterly lost. Then a gang of punks surrounds him, but he quickly learns that he doesn't have any of the powers that he thought all people transported to a parellel world should have. Just when he's about to be beaten senseless, a girl appears...

After being attacked by someone the first time, sliced open by Elsa the second time, and stabbed in the back by punks the third time, Subaru should have been dead, but found himself back where he started in the same parallel world every time. He finally realizes he's acquired the power to go back to the time and place he started from, which he calls "Return by Death." In hopes of changing the fate awaiting Felt, Satella, Old Man Rom, and himself, Subaru takes off for the fourth time.

Subaru attempts to buy the insignia from Felt and return it to Satella before Elsa arrives at the loot house... but Satella arrives before the negotiations are complete, and Elsa still attacks them.

After being badly wounded by Elsa, Subaru somehow survived and awoke in the mansion of Margrave Mathers, in the Kingdom of Lugunica.

Subaru now lives and works in Roswaal's mansion, working with Ram and Rem, and finally getting Emilia to agree to a date with him. But the day of their promised date never comes as Subaru keeps going back to the day he first awoke in the mansion. He's confused at the thought that he Returned by Death despite having no memory of experiencing anything deadly, but he's determined to repeat his previous actions up to the point of fulfilling his promise with Emilia.

Subaru's first day at the Roswaal mansion begins for the third time. The first time, he grew weak and died of unknown reasons in his sleep, and the second time, he was killed by an attacker. The sound of chains that he heard as he died the second time replays in his mind, waking him in a terrified, cold sweat. He has no idea what the killer is after, let alone who it is, so he makes a plan to leave the mansion on the fourth night and watch for the attack to happen.