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. \ Standing before Subaru is someone he never expected. The truth of the attacker's identity leaves him bewildered, and he feels everything crumbling around him as he dies yet again. Then, for the fourth time, he awakes on his first day at the Roswaal mansion. This time, the night of the fourth day passes without incident, and Subaru is stunned as he greets the morning of the fifth day... but then the situation takes an unexpected turn.

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... \ The scattered pieces of the puzzle finally come together, and Subaru realizes for certain that the shaman who cursed him is in the village at the foot of the mountains. He heads there with Ram and Rem and makes sure all the villagers touch him so that he can find out, with Beatrice's help, who cast the curse. But the truth he finds is not what he expected, and he finds himself rushing toward the village again...

Subaru risked his life to save the children from a pack of Ulgarm, but he was so powerfully cursed that there could be no saving him. Even Beatrice is unable to undo the complex web of curses on him, and says he'll grow weak and die within half a day. The only way he can survive is if the entire Ulgarm pack is defeated, but time is not on his side. Subaru is ready to give up when he learns that Rem has gone into the forest by herself... \ Knocked unconscious by Subaru's attack, Rem dreams of an event in her past that she and Ram would rather forget... a sin for which Rem feels she can never be forgiven. After waking up, she tells Subaru that she's just committed the same sin again. When the three of them are moments from being cornered by the Ulgarm pack, Subaru takes off to draw their attention so Ram and Rem can escape.

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. \ As Emilia joins Priscilla, Crusch, and Anastasia in a meeting of the royal selection participants, Reinhard enters the hall with Felt. According to a new prophecy seen on the Dragon Stone, there are five priestesses with the potential to be the kingdom's next ruler. Reinhard announces that Felt is the fifth priestess, meaning it's time to formally begin the royal selection, but Felt refuses to have any part in it.

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... \ Upon returning to Roswaal's mansion, Subaru is greeted by an unbelievable sight and wails that this was not what he wanted to happen. Stricken with despair, everything before Subaru starts to go white as, finally, he hears a voice: "You were too late."

Subaru awakens in front of the fruit stand in Lugunica's capital yet again. Realizing that he's in a hopeless situation, he desperately seeks help from Crusch, Priscilla, and Anastasia, but his limited time continues to tick away... \ A mysterious figure appears before Subaru and his traveling companions. As the looming beast attacks with a deafening bellow amidst the darkness and fog, Rem determines that it will be too difficult to escape...

Subaru laments that he could not do anything or save anyone, and has no options left. Exhausted, he suddenly takes off running at full speed as if he's made a decision... \ To save Emilia, Subaru approaches Crusch to negotiate the formation of an alliance. His terms are a bit difficult for Crusch to believe, but she can see that Subaru isn't lying.

Subaru has devoted everything he had, and done all he could do. His passion has captured Crusch's heart, as well as Anastasia's cooperation, and they all enter into the battle against the White Whale together. \ Subaru and Rem lose all words at the sight unfolding above them. Just when it seemed they would soon have the White Whale cornered, despite the sacrifices it took to reach that point, the battle takes a turn that no one expected.

The half of the mercenary army that had been blocking the road during the White Whale subjugation returns to join the main force. Subaru then leads the way into the forest of the Mathers domain, hoping to find and destroy the Witch's Cult before they can learn of the subjugating army's movements. Subaru and his companions head toward Roswaal's mansion to evacuate Emilia and all the others there, stopping at the nearby village on the way and beginning to evacuate its residents as well. However, the situation takes a turn that nobody expected...

Emilia tried to warn the villagers of Arlam that danger was coming and they should evacuate, but was not well-received. As she's pondering what more she can do, Wilhelm arrives at the mansion with a message... Subaru and Julius face off against Betelgeuse's Unseen Hand. However, as one Unseen Hand after another is launched their way, the two heroes find themselves completely on the defensive.