Tragedy strikes the Sanctuary, and Elsa takes aim at both Roswaal's mansion and the village of Arlam. After being told that all these threats are cruel traps, Subaru can't help but give in to despair. While he's stuck questioning himself and unable to come up with a way out of the dilemma closing in on him, Otto shows up and punches him. Thanks to the many feelings packed in Otto's fist, Subaru finds his hope again.

Having been born with the "soul of language" divine protection that allows him to converse with non-human creatures, Otto Suwen's life has truly had its ups and downs. After being run out of his hometown because of his ability, he found his independence as a merchant, was attacked by the Witch's Cult, met Subaru... and now, his life is literally on the line in a deadly game of tag. To fulfill his part of the plan, Otto must evade Garfiel's vicious attacks in a desperate effort to buy time.

The missing Emilia was in the graveyard all along, her lost memories beginning to return due to Puck's disappearance. Confused and losing heart over the realization that she's forgotten such important memories, she tries her hardest to convey her feelings to Subaru. When the two of them leave the graveyard, they're awaited by Garfiel, who's been battered and beaten by Otto and Ram. He tries to prevent the Sanctuary's liberation by closing off the graveyard himself, but Subaru won't let him have his way without a fight.

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.

Despite a few inconveniences, like being unable to go outside when she wanted, young Emilia lived a happy life in a settlement of elves with Fortuna, whom she lovingly called "Mother." However, their peace was threatened by the arrival of the Sin Archbishop of the Witch's Cult representing Greed, Regulus Corneas. In the present, Shima appears before Subaru and the others as they wait outside the graveyard for Emilia to complete the trial, and she tells them of the events leading up to the birth of the Sanctuary.

Pandora, the Witch of Vanity, stands before Geuse and Fortuna. They both face her with all the strength they have. Meanwhile, young Emilia runs toward the place where the seal is, believing that everyone will be saved if she gives Pandora what she wants. But when she arrives, Pandora is already there, insisting that she hand over the key to opening the seal.

When Roswaal happily tells the story of how his romance with Echidna began 400 years ago, Beatrice rebukes him for casually calling it a "romance." Ryuzu interrupts to comment that Echidna saved her, as well. The one thing these three very different people share is their gratitude toward Echidna. But their days spent in both amicable and argumentative conversation about Echidna are brought to an end by one man's arrival.

Subaru tries to prevent the attack on the mansion by talking to Roswaal, but Roswaal refuses to let go of the wish he has clung to for 400 long years. Subaru takes Garfiel and Otto along as he hitches up the carriage to Patrasche and heads for the mansion as quickly as he can. Meanwhile, now that Emilia has completed the first trial, Ram asks her for a favor. Touched by the strength of Ram's feelings, Emilia reaches out to help her.

Frederica is gradually backed into a corner by Elsa's attacks. Then Garfiel rushes to the scene with a silver shield on each arm. The siblings' reunion after so many years is cut short when Elsa's knife violently clashes against Garfiel's shield. Meanwhile, Subaru heads to the forbidden library where Beatrice is. She's surprised when he enters the library and tells her that, after she spent 400 years there under a contract that might as well have been a curse, he's going to get her out.

After witnessing an unrealized present, Emilia completes the second trial and begins the third and final one. Ram and Puck are fighting their hardest to stop Roswaal. Each of them is doing it all for the sake of realizing their own goals. The battle between Garfiel and Elsa at Roswaal's mansion is also growing more and more intense. As Subaru is being chased by a guiltylowe, he declares that it's time to make use of his unparalleled knowledge of the modern world and lures it into a closet...

After completing the final trial, Emilia emerges from the graveyard into a blizzard heavy enough to block her vision. The people of the Sanctuary and the villagers of Arlam huddle together behind a giant wall of ice, created to shield them from the bitter cold by none other than the great spirit who was once contracted to Emilia. When Emilia touches the ice wall, something flows into her from within it. With a nod of acknowledgement to the voice she hears, she finally takes action.

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.