Re:Zero season 4

Following the Battle of Priestella, Julius' name was consumed by Gluttony, leaving him forgotten by everyone besides Subaru. To cure Julius, along with the other victims of Gluttony and Lust, Anastasia proposes seeking out the legendary Sage, Shaula. Subaru, Emilia, Beatrice, Anastasia, and Julius head back to Roswaal's mansion to prepare for the journey to the Pleiades Watchtower, where Shaula is said to reside. Along the way, Subaru also deduces that an artificial spirit Anastasia is contracted with is possessing her—a copy of Echidna in the form of a fox, whom Subaru nicknames "Foxidna". Foxidna explains that Anastasia's consciousness has gone dormant and the possession is gradually consuming the latter's lifeforce; thus, she seeks Shaula for a method to awaken her. After arriving at the mansion, Subaru decides to bring the comatose Rem along on the trip, wanting to be there when she wakes up. He also recruits Meili to help traverse the mabeast-infested Auguria Dunes surrounding the Watchtower.

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Meanwhile, back in Priestella, Garfiel and Mimi visit the former's mother and bond with her new children, Fred and Rafiel, before parting ways.

With Ram joining them, Subaru's party sets off for the Auguria Dunes. After several days of traversing the desert, the group deduces that the area is under a huge spatial magic that prevents them from reaching the watchtower. Having been told by a local that birds have been spotted reaching the tower, Subaru has Ram use her clairvoyance on one, allowing them to find the way through. Unfortunately, they then find themselves surrounded by a pack of mabeasts, forcing them to flee until a flash of light from the tower snipes Subaru in the head, killing him. Respawning just before the chase, Subaru, Beatrice, and Patrasche take a different path towards the tower, only for the light to kill all three of them. Respawning again, Subaru successfully avoids the entire chase this time before having Ram use her clairvoyance to detect who is targeting him, allowing Emilia and Julius to deflect the first shot. Subaru and Beatrice erect an anti-magic field to neutralize more shots, but this interferes with the area's spatial magic, opening a rift that the group falls into. Meanwhile, at the watchtower, the girl who has been killing Subaru notes that she "found him".

Separated from the others and finding himself in an underground passage with Ram, Foxidna, and his land dragon, Patrasche, Subaru and his companions search for an exit. Going right after encountering a fork in the road, they encounter multiple closed doors that mysteriously open when Subaru interacts with them, until they reach one that refuses to open for some reason. Concurrently, the group grows strangely fatigued and anxious, leading to a fight between Subaru and Ram, resulting in Foxidna fatally stabbing the latter. However, Ram survives and bisects Foxidna, killing her. Patrasche then kills Ram before she can kill Subaru, only for the land dragon to turn on Subaru and kill him herself. Returning to before they turned right, Subaru deduces that the path is laden with madness-inducing miasma and convinces the others to go left this time. However, this leads them to cross paths with a powerful centaur-like mabeast. Fortunately, a girl from the watchtower appears and kills it, after which Subaru loses consciousness from fatigue.

Following a strange dream featuring the people whose witch factors he absorbed—Satalla, Petelgeuse, and Regulus—Subaru wakes up at the watchtower to find that his group has reunited with the others. He then meets the girl who saved him, who mistakes him for her "master", whose return she has been awaiting for 400 years, due to the miasma from his recent deaths. The girl reveals herself to be Shaula but clarifies that, contrary to common belief, she is merely the sage's disciple; the actual Sage was her master, a man named Flugel. Though Shaula cannot help them, the party concludes that they might obtain the knowledge they seek from the tower's library. However, they find that accessing it requires solving a riddle left by Flugel: "Who is the hero Shaula defeated"? While the others cannot make sense of it, Subaru deduces that the riddle refers to the star Shaula and concludes that the hero is Orion from Greek mythology. Having solved the riddle, the group is then teleported to the library.

Since Flugel's riddle used knowledge from Earth, Subaru concludes that the sage must have been transported to this world like himself. Exploring the library, he is shown Typhon's memories after picking up a book titled after the Witch of Pride: raised by an executioner, she developed a twisted morality that made her manifest the power to shatter anyone who considers themselves a "sinner". Deducing that these "Books of the Dead" contain the deceased's memories, the group searches for one with the answers they seek, but finds nothing. Concurrently, Subaru attempts to bond with Meili, prompting the latter to reveal that she was abandoned by her parents and raised by mabeasts. Foxidna also deduces that the tower has rules, and Shaula is contracted to kill those who violate them: 1. They cannot leave before completing all the exams; 2. They cannot violate the rules; 3. They cannot vandalize the library; 4. They cannot damage the tower. Concluding that completing the exams is their only option, the group takes the second exam on the next floor: a duel against an individual materialized by the tower, who calls himself a "Stick Swinger".

Julius accepts the Stick Swinger's challenge but gets utterly defeated despite Foxidna attempting to support him with magic. Emilia then takes the exam and successfully lands a hit on the Stick Swinger when he lets his guard down, after which he announces that she passed and grants her access to the top floor. Afterward, with the others denied access until they pass as well, the group moves to another floor to discuss strategy, during which Shaula reveals the Stick Swinger's identity: the Astrea family ancestor—the original sword saint, Reid Astrea. Meanwhile, Julius slips away and retakes the exam only to be repeatedly beaten by Reid, plummeting his already-damaged self-worth after his name was eaten. In the end, Subaru arrives and takes the injured Julius back with him. While Julius initially rejects Subaru's aid, he ultimately relents when the latter remains insistent about helping him.

After getting Julius' injuries treated, Subaru checks up on his companions and agrees to keep watch as they sleep, only to slumber away himself. Upon waking, he finds Foxidna is gone and eventually finds her atop a balcony by following one of the birds nesting at the tower. Now in private, the two openly voice their distrust for each other, with Subaru wary of her being a copy of Echidna while Foxidna is suspicious of his unknown origins. Julius then finds them and, having overheard them discussing Anastasia's condition, demands an explanation. This prompts Foxidna to come clean to Julius, causing him to relent but also leaving him distraught about failing to notice his mistress's condition. After Julius and Foxidna take their leave, Subaru brainstorms a way to pass Reid's exam and rushes off somewhere after having an idea. The next day, Subaru is woken up by Emilia and Beatrice. However, he does not recognize them and then excitedly realizes that he is in another world, having seemingly lost all of his memories since being transported from Earth.

Deducing from Emilia and Beatrice's reactions that he has amnesia, Subaru is nevertheless excited about being in another world. However, upon being reintroduced to his comrades, Julius and Ram are respectively devastated that he and Rem have now been forgotten by everyone. Foxidna also comes clean about herself and Anastasia's situation. Learning he had collapsed in the library, Subaru heads there to hopefully find the cause of his amnesia. However, on the way, someone pushes him down a staircase, killing him. Respawning when he woke, Subaru believes he had a prophetic dream and repeats the previous loop, but cannot find his attacker. However, upon regrouping with the others, he overhears them calling him a liability before someone once again pushes him down the stairs. Respawning again, Subaru becomes paranoid and runs away, only to get beaten up by Reid after accidentally entering his exam and being silenced by Satella when he talks about having died. After being found by Emilia and having his injuries healed, Subaru deduces Return by Death's mechanics and flees the tower, unknowingly breaking its rules. Meanwhile, in the library, Shaula suddenly collapses.

Subaru is attacked by mabeasts upon exiting the tower and gets rescued by Shaula. However, he subsequently falls into a sinkhole and momentarily blacks out. Waking up in the miasma-filled underground passage, he finds himself surrounded by mabeast corpses and now able to open three of its doors instead of the previous two before suddenly being teleported back to the tower. Influenced by the miasma, the paranoid Subaru resolves to kill his companions. However, he comes to his senses upon discovering that Shaula, Ram, Julius, Meili, and Foxidna have all been killed, causing him to second-guess whether one of them was his attacker. The tower then starts getting destroyed as Subaru is mockingly confronted and beheaded from behind by a seemingly now-awake Rem. In the next loop, Subaru hides his amnesia and investigates his companions to find his attacker. However, Subaru blacks out again when Meili confronts him alone and awakens to discover that he strangled her to death before noticing the words "Subaru Natsuki was here" etched into his forearm.

Believing the "real Subaru's" consciousness momentarily returned and killed Meili, Subaru hides her corpse before being confronted by Emilia, who has deduced something is wrong and tells him to confide in her. However, the others then inform them that the library has materialized Meili's Book of the Dead, revealing her fate. To hide his involvement, Subaru volunteers to read it: raised by mabeasts and recruited into an assassin organization by Elsa and their leader, Capella, Meili joined the expedition due to not knowing what to do anymore following her capture until last night, when an out-of-character Subaru told her to "follow her desires", culminating in him killing her after he began acting strange again when she attempted to continue their conversation. Afterward, Subaru is haunted by visions of Meili while the others fruitlessly search for her corpse. He also contemplates killing the others and reading their books to find out what they truly think of him. That night, Subaru checks on Meili's corpse to find that it is gone before being confronted by Ram, who has deduced that he is not the "real Subaru", causing him to consider killing her to protect his cover.

Subaru reveals he has amnesia after getting restrained by Emilia when he attacked Ram. However, while Emilia believes him, Ram does not, leading the girls to fight. Getting knocked out in the crossfire, Subaru wakes up alone later to find the tower under attack by mabeasts. Julius faces them until Reid, who was confined to his exam but can now move freely, kills them all and resumes his duel with him. Subaru meets up with Beatrice and Foxidna before getting attacked by a scorpion mabeast, resulting in both girls being killed whilst driving it off. Concurrently, the imaginary Meili continues to mock Subaru. Satella then appears and begins to devour Subaru with her miasma, but Emilia saves him. However, Subaru has given up, admitting that his suspicions of the others were wrong and just wanting to die now. In response, Emilia tells him about everything they went through. However, he believes himself incapable of such accomplishments until she confesses her love to him, causing him to realize what had changed since coming to this world: he had fallen in love with Emilia. The miasma then devours them, killing them both. Subsequently, after respawning, Subaru vows to save everyone this time.