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.

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 in Roswaal’s mansion begins for the fifth time. Determined to save everyone this time, he makes it a point to keep his best smile on his face in order to earn the trust of the mansion’s staff. But although he works his hardest to make them like him, his body begins to have trouble keeping up with his heart’s intentions. Soon Emilia is unable to bear the sight of him struggling any longer and takes an unexpected action…

Amid dying countless times, Subaru finally led the troops to victory against the White Whale and struck down the schemes of the Sin Archbishop of Sloth. After overcoming a painful ending to his these ordeals, he was reunited at last with his beloved Emilia… only to learn that Rem’s existence had been erased from the world, wiped out by the White Whale somewhere in the middle of his death loop. And now that the White Whale is defeated, Subaru and the others face a crisis no one could have expected.

As she attempts the first trial, Emilia finds herself in Elior Forest, where she lived when she was younger. Echidna snidely remarks on her audacity to set foot here after so thoroughly disgracing herself before, but Emilia responds with a bold smile and tells her she won’t cave to the malice of a fellow witch. As they proceed deeper into the forest, they come upon a massive tree towering over its surroundings. At its base is a small, barred door, which Emilia identifies as the Princess Room where she was often sent to play as a child.

The magic Roswaal is using to control the weather generates enough mana to attract the Great Rabbit, which draws closer to the Sanctuary in a massive horde. Emilia takes Roswaal and Ram to shelter in the graveyard with everyone else, but the Great Rabbit horde has already grown enough to engulf their surroundings. Just when all hope seems lost, Subaru and Beatrice appear before Emilia. So begins Subaru and Beatrice's first battle against the Great Rabbit, one of the Three Great Mabeasts.