The SE.RA.PH. Singularity is a Subspecies Singularity (亜種特異点, Ashu Tokuiten?, localized as "Pseudo Singularity") of the Remnant Order dealing with the aftermath of the Human Order Incineration Incident in Fate/Grand Order. Originating on Chaldea's Seraphix facility in the North Sea, it occurred in the Mariana Trench, supposedly in 2030 A.D.
The events of Ritsuka Fujimaru's visit to this Singularity are covered in an event of Epic of Remnant; Deep-Sea Cyber-Nirvana: SE.RA.PH. (深海電脳楽土 SE.RA.PH , Shinkai Den'nō Rakudo?, localized as "Abyssal Cyber Paradise: SE.RA.PH."), alternatively Epic of Remnant/EXTRA.
After escaping the Time Temple along with three other Demon Gods, Zepar sought to help humanity realize their mental potential. However because he lost his body, he needed to seek refuse somewhere to regain his strength. He eventually found Seraphix, an oil rig secretly containing a planetarium called Celestial Body Simulator, System Animusphere, which was used to investigate leylines. There he found Kiara Sessyoin, a therapist who worked at Seraphix, and possessed her to avoid Chaldea's detection. He then used her to eventually effectively gain control of Seraphix. Using his knowledge of parallel worlds, Zepar discovered another version of Kiara, one who usurped control of the Moon Cell on the far side of the Moon. Impressed by her, he linked the two Kiara together, and used her body to convert Seraphix into SE.RA.PH and give it form. Afterwards though, Kiara plunged the Seraphix staff into mass hysteria to Zepar's disgust. She then seduced the personnel to open the planterium, where she placed 128 Master candidates in the Coffins found there to summon 128 Servants, which killed them. As well BB, Meltryllis, and Passionlip were salvaged from Kiara, as she had absorbed them in the Moon world, to serve her. Jealous of the delight she felt from Zepar's memories, Kiara sought to use SE.RA.PH to become a Beast. Zepar realized at this point that he lost control of Kiara's body, and he was forced to reside only in her pinky finger. Eventually though he was forcibly expelled, and quickly disappeared. Kiara then enacted her plan to descend SE.RA.PH down into Earth's core so she may fuse with the planet. She infected Meltryllis and Passionlip with parts of her, Karmaphage, to turn them into Sentinels to serve as SE.RA.PH's self-defense mechanisms. She also ordered BB to begin the Holy Grail War while continuing to manage SE.RA.PH. At some point though, the Moon Cell sent a copy of the original BB to Seraphix on a one way mission to prevent Kiara's transformation into Beast. She then switched places with the other BB as manager of SE.RA.PH while the other hid at its bottom.
BB recreated the Moon Holy Grail War, but compared to its original more organized battle royale counterpart, this one turned into a massacre. The Servants succumbed to their desires, and began to commit several atrocities. One particular Servant by the name of Suzuka Gozen was turned into a Sentinel by BB, hoping to win the Grail War for her Master, not knowing they were already dead. Meanwhile, the corpses of the Masters inside the still active Coffins were used as biological circuits to continuously summon Servants. Eventually Meltryllis and Passionlip decided to rebel against Kiara, and became the Servants of a version of Ritsuka. They eventually won the Holy Grail War, and fought Kiara at the planetarium. They lost however, and BB's time leap failed due to Meltryllis and Passionlip still being Sentinel. Meltryllis's arms were torn apart, and Ritsuka was killed for her transgression. Passionlip then used Virgin Laser - Palladion to launch Meltryllis upwards at the speed needed for time travel. Meltryllis vowed to redo everything so she can help Ritsuka free the Sentinels from Kiara's influence. She then met a past version of herself at the chapel, and shared her memories with her. The past Meltryllis then committed suicide without hesitation to prevent Kiara from realizing there were two Meltryllis.
Chaldea prepares for their regular report from Seraphix. It is an Offshore Oil Rig once owned by the Animusphere family that provides Chaldea with resources. Chaldea attempts to contact the facility, but they receive no audio or visual, despite both feeds being active. They receive an SOS message, saying everyone is being digitized. The connection with Seraphix is then abruptly cut, so Leonardo da Vinci authorizes the use of Sheba to observe Seraphix. However, Seraphix seemingly no longer exists, with no signs of a Singularity. Chaldea soon receives a video message from BB. She reveals Seraphix no longer exists in the current time period, and tells Chaldea to check the Mariana Trench in 2030 A.D. The staff confirm Seraphix's location, revealing its currently 200 meters below the surface along with the existence of a Singularity. BB tells Chaldea to save Seraphix's staff before the oil rig sinks down to 10,000 meters while also dealing with the Singularity manifesting there. Da Vinci explains rayshifting to the future is impossible, but quickly realizes BB can verify Ritsuka and others' existence since 2030 is BB's present. BB warns Seraphix will reach the bottom of the trench in a few hours, at which point it'll be destroyed by the water pressure. Ritsuka, Nero Claudius, Tamamo-no-Mae, and EMIYA then rayshift to Seraphix. However BB hacks the rayshift to separate the group to random locations in the facility.
Ritsuka arrives in a strange locale when they're contacted by BB. She tells them they're a Holy Grail War, a battle to the death between 128 Masters. She then explains they're in Seraphix, but it's been digitized into Pseudo-Spiritrons. They'll retain nearly everything they gain once they return to the physical world. BB reveals they're at what was once Seraphix's front gate. She tells them to discovery the mystery of the digitization before SE.RA.PH sinks to the bottom of the trench while surviving through the Grail War. After BB ends communications, Ritsuka tries to find Nero, Tamamo, and EMIYA when they're ambushed a female swordsman. They're saved by another girl, revealing their assailant is Suzuka Gozen. The girl introduces herself as Meltryllis, and has Ritsuka contract with her. She then fights Suzuka, but her attacks are reduced by 90% by Suzuka's karmaphage. Suzuka retreats however when Meltryllis said her attacks have deadly viruses. Meltryllis decides they should enter the facility from the main oil deck cable area, given the front gate is completely digitized. She warns Ritsuka that they'll eventually be disintegrated if they stay too long in digitized areas. In such areas, humans are converted into data after a few hours and imported to SE.RA.PH. Even Servants will only last a few days. Meltryllis warns everyone will be converted into data well before SE.RA.PH reaches the bottom of the trench. She reveals time in SE.RA.PH passes a hundred times quicker than in reality. She also explains SE.RA.PH is based on Seraphix, though it's significantly larger. The pair then search for a safe haven before Ritsuka is digitized.
Later, Meltryllis explains that SE.RA.PH is a digital labyrinth loosely based off of Seraphix. However, the current SE.RA.PH is only an imitation. The original is an engine designed to operate the Moon Cell, a construct of photonic crystals inside the moon. It was the site of the Moon Holy Grail War, the Moon Cell itself being the prized Holy Grail. However, while that Grail War operated like tournament, the current one is a free-for-all. The pair then encounter Gawain, who wasn't among the 128 Servant. He claims he was one of the three Servants who rayshifted with Ritsuka, though their memories say otherwise. The group decide to search for Ritsuka's other Servants in addition to finding a safe area. BB then suddenly appears, and decides to punish Ritsuka for breaking the rule of having more than one Servant. She then summons Robin Hood and orders him to kill the group. After they kill Robin, BB claims she'll let Ritsuka go free if they either win her Grail War, or discover the secret behind SE.RA.PH. She reveals she locked several passageways that she'll discreetly open for a fee. She also explains that SE.RA.PH is like the digital embodiment of humanity's inner world, once called the Sakura Labyrinth. It and the Sentinels convert human emotion into defensive mechanisms. Each Sentinel is granted a powerful passive skill called Karmaphage, which makes them nigh unbeatable to a normal Servant. There are five in total, each guarding 1/5 of SE.RA.PH. BB then resurrects Robin and sends him away. Before leaving, she reveals Chaldea cannot rayshift past the year 2019.
Later, Meltryllis explains most Servants in SE.RA.PH have fallen into depravity. She also reveals the Masters died long ago when they summoned their Servants. The group come across what Ritsuka assumes is a Grail. Upon touching it, they see the final memories of a Seraphix crew member. On January 2019, Seraphix became isolated from the world, and the digitization began. By February, the crew was down to about a hundred survivors, and most of Seraphix was digitized. By March, the crew grew violent, and executed many due to minor transgressions or hysteria, including director Hideyasu Ajima.
The group eventually come to a fork; one path leads to the Chest while the other leads to the Thighs. Meltryllis reveals the current area, Hair, is relatively safe, but the Chest may have survivors. The group are then confronted by Tristan, who tries to kill Meltryllis. They fight him until Ritsuka and Gawain convince him to join. Tristan reveals he was summoned in SE.RA.PH. ten days ago. He seeks to capture BB, while killing any insane Servants he encounters. He then recalls encountering an Alter Ego many times, each time forced to retreat to avoiding being crushed. He calls the path to leading the Chest, Breast Valley, the Alter Ego's domain. Meltryllis reveals the Alter Ego is Passionlip.
The group come to Breast Valley when Ritsuka begins to feel the effects of digitization. A woman then appears, and believes Ritsuka's Servants are insane like the ones she encountered so far. She calms down though when notices Ritsuka is wearing a Chaldean uniform. She introduces herself as Marble Macintosh, robotics operator on Seraphix. She begs Gawain to kill Meltryllis, asserting humans and egos are mortal enemies. However, her pursuer, Passionlip, soon catches up to her. Passionlip also crushed the new 128 Servants when they arrived. Meltryllis reveals Passionlip is a Sentinel. The group fight her, but they're forced to retreat when she uses Trash & Crash on the passageway. With the passageway now compressed into a cube, the group return to the fork with Marble.
Later, Marble reveals the one only survivors beside her are Arnold Beckman, Ms. Trapayne, and Holly since they stayed in the Central Command Room. However, the only people left in the Command Room are her and Arnold before she ran away when food got scarce. Meltryllis reveals there is a chapel in the Thighs that can be used as a safe haven since it has magical protection and too many indecipherable elements to be digitized. However, Vlad III guards that area, so he must be defeated if the group wish to get to the chapel. They eventually encounter Vlad and defeat him. Before disappearing, he reveals EMIYA is in the chapel, though he is not be trusted.
The group enter the chapel, only to find EMIYA Alter. He explains BB switched him for his regular self. He reveals there is a terminal hidden behind the altar that contains a report. However it is locked to even Servants and Alter Ego, so its key needs to be found. The group believe the report may contain a clue, and decide to search for the key tomorrow.
After purchasing the terminal key from BB, Ritsuka uses it on the terminal. Marble explains it sends data directly into viewer's brain. The record is from February 7, 2019 by a therapist who joined Seraphix in 2016. The chapel used to be her place of work. She tried to help the crew when Seraphix became isolated from the world on January. By Feburary, she lost her morality, but obligations helped keep her rationality. On March however, she was severely injured and locked inside the chapel. She fears something worse than the hysteria is eating away at her mind. She then begs somebody to stop the planetarium and its experiments. After the record ends, Gawain believes the crew summoned BB of their own accord. Meltryllis reveals the planetarium is in the middle of SE.RA.PH, and it's the source of the digitization. Ritsuka, Meltryllis and Gawain decide to continue exploring while Tristan and Marble stay in the chapel. EMIYA Alter leaves to kill the Servants.
The group discover the upper part of the Arm. BB contacts them, and introduces them to the next Sentinel, Tamamo Cat. After Cat is defeated, BB sends her down a trap out of annoyance that she didn't use her Karmaphage. She reveals she summoned the new 128 Servants that were promptly crushed by Passionlip earlier. She will continue to summon until a proper recreation of the Battle of the Time Temple is made. She warns there's only one real world hour left before SE.RA.PH hits the seabed before ending contact.
Eventually, the group make it to the Flank Seperator, which used to house devices for desalination and resource collection. A memory then appears that Ritsuka promptly touches it. It is the memory of a man who was brought to Seraphix to serve as a fixer; someone who kills those who disrupt operations or leak secrets. He recalls the survivors dividing into factions, and himself becoming Beckman's enforcer when he took control. He eventually became hysterical and paranoid thanks to the manipulations of a particular woman.
Joined by EMIYA Alter, the group near the area's final zone. Meltlilth explains Alter Egos were originally salvaged to be Sentinels. However, a Sentinel doesn't need to be Alter Ego. They just need a Spirit Origin that can handle a Karmaphage. The group eventually encounter Cat and fight her. After she is defeated, EMIYA Alter seemingly fatally shoots her. However, she lives because he used his knowledge of Magic Circuits to target and destroy the parts of her Spirit Origin infected by the Karmaphage. Now free of BB's control, Cat joins the group.
Returning to the chapel, the group note the only areas left to explore are the soil survey room, the resource compression and drying area, and the dump. Meltryllis reveals SE.RA.PH. has a two layer structure, with a front side and back side. She was a back side Sentinel before BB scrapped her for disobedience. Humans and Servants cannot cross the border between the sides though, only Sentinels can. Thus, the only way to get to the back side would be to flip SE.RA.PH over. Ritsuka realizes there is a way to flip SE.RA.PH. Meltryllis reveals they can reach the Command Room through the back side, where they can flip SE.RA.PH. again to arrive at the Chest. While this method will help them bypass Breast Valley, they'll still need to fight Passionlip. She'll will join though if her restraints are destroyed.
Joined by Cat and EMIYA Alter, the group arrive at the Flank Separator. Ritsuka hits the Separator, and SE.RA.PH starts shaking. BB sends a Sentinel, Elizabeth Bathory, to punish them for their transgression. The group defeat her, but Passionlip begins approaching. Gawain holds her off, while Ritsuka successfully flips SE.RA.PH.
Arriving on the back side, the group are greeted by Suzuka. She ignores BB's orders to escort them and fights them. After the fight, she is ordered by BB to return to the temple. She tells the group to check out the Nape if they plan to head to the Command Roon. She then leaves saying the Seraphix's crew brought the crisis on themselves, and Seraphix was never just oil rig. The group soon come to a gate reserved for employees that reported directly to the Animuspheres. They're forced to destroy its defenses when they fail present identification. They eventually meet Robin again. He warns Passionlip is waiting for them on the front side. He also reveals BB developed a weapon that can break "the shackles" on Passionlip's heart, along with her restraints. He then takes everyone except EMIYA Alter back to the front side. BB then offers EMIYA Alter a chance of survival if he kills every surviving human on SE.RA.PH, and captures Ritsuka. If he does that he'll learn the secret about SE.RA.PH, as part of his job as Counter Guardian. EMIYA Alter promptly agrees to join BB.
The group arrive back on the front side being approached by Passionlip. BB reveals the only way to defeat Passionlip is to use the Maiden Coaster, a battle to conquer the mind. It is connected to the Code Cast Ritsuka bought earlier. They only need to place their hand on Passionlip's chest, but the group will need to pin her down first. Gawain arrives to hold Passionlip long enough for Ritsuka to touch her chest. Upon doing so they're converted into Psuedo-Spiritrons by BB in order to enter Passionlip's mindscape. After being defeated there, Passionlip collapses followed by Gawain, though he quickly recovers. After Cat returns to the chapel carrying Passionlip, Robin sneaks off somewhere. Ritsuka, Meltryllis, and Gawain then continue onto the Command Room.
Inside they find and kill a Demon God. They then meet Arnold Beckman, secretary to Hideyasu. He tries to stops the group from viewing the room's records by asserting only those authorized by the Animusphere's head can access them. He also insists the planetarium doesn't exist. Meltryllis however reveals the data was deleted long before they arrived, leaving them on their own to find the planetarium. She then finds a passcode for the chapel terminal. Beckman reveals the Demon God suddenly emerged from the floor one day. It killed and consumed the people who murdered the doctors. Beside that, it left the others alone if they kept their distance. Ritsuka and Gawain noticed it felt empty compared to the other ones. The group then return to the chapel with Beckman.
Back at the chapel, Ritsuka accesses the record on the terminal. It is from the therapist under possession of Zepar, recorded in her sleep through an unknown method. Seraphix contains a secret mage's workshop in its depths to conduct a certain experiment. It was kept secret to avoid the watchful eyes of the Lords, and the experiment could only be conducted on the seabed. Among the resources brought into Seraphix were humans of varying Magic Circuits and Rayshift compatibility. Several days after being locked in the chapel, the therapist was contacted by Zepar. He wished for humans to realize their mental potential, though his body was destroyed. He then possessed the therapist to regain his strength, and used her to digitize Seraphix. He then rayshifted Seraphix to 2030 to prevent Chaldea from discovering his plan. From there, it will sink down into the Mariana Trench, and once it reaches the bottom, Zepar will be reborn. Zepar then disposed of the therapist after BB was summoned to be his new partner. After the record ends, Meltryllis confesses she knew Zepar summoned BB to serve as his navigator by running SE.RA.PH. BB however placed restrictions on her and Passionlip to prohibited them from revealing SE.RA.PH's true origin and purpose. She is surprised though BB allowed a record revealing Zepar's plan to exist. EMIYA Alter surmises Zepar somehow learned of the Moon Holy Grail War from an different timeline, and summoned BB to transform Seraphix into SE.RA.PH so he can be reborn. Meltryllis reveals BB summoned Servants to procure the Psuedo-Spiritrons needed to keep SE.RA.PH running. The group decide to defeat the Sentinels and BB before stopping Zepar's plan. Later while the others are resting, Gawain is ambushed and consumed by something.
The next morning, everyone discovers that Gawain was killed while they were sleeping. Meltryllis and Passionlip are accused by everyone except Ritsuka and Cat because they're Alter Egos. Meltryllis asserts they were outside at the time, and Gawain was too wary of her to allow her to ambush him. Seeing the lack of evidence, Tristan asks Ritsuka to continue exploring SE.RA.PH while he continues to stay behind to protect Marble and Arnold. He also asks EMIYA Alter to accompany Ritsuka so they can keep an eye on him. He is suspicious of both the Alter Egos and EMIYA Alter, but he understands the Alter Egos wish to protect Ritsuka while EMIYA Alter isn't especially concerned. Thus, he'll have the Alter Egos protect Ritsuka while EMIYA Alter keeps an eye on the Alter Egos.
Returning to the back side, the group head towards the Spine, the center of SE.RA.PH. Suzaka's temple is there, and she is charged with the back side. However, the group find the Spine has been gated off. They're then contacted by Beckman via equipment Tristan brought back from the Command Room. He orders them to flip SE.RA.PH. once they're at the spine, saying they should arrive at the planetarium. He also reveals SE.RA.PH will the reach the bottom of the trench in 15 real world minutes, or 24 hours in SE.RA.PH time. He ends his transmission saying he'll meet them at the planetarium.
Entering the Spine, the group soon arrive at Suzuka's temple. She reveals she and Tristan are the only Servants left in the Grail War. She proves too fast and strong for the group to pin her long enough for Ritsuka to open her Maiden Coaster. Arnold suddenly contacts them to warn SE.RA.PH has started to sink faster, so he orders them to defeat Suzuka quicker. Cat uses her ultimate technique to trap Suzuka in response to her conviction to win for her Master. Ritsuka uses this opportunity to open Suzuka's Maiden Coaster with the key they bought from BB earlier. After she's defeated in her mindscape, Suzuka tries to jump off a cliff. Cat stops her though, and convinces her to join them. Suddenly, a Demon God emerges from the ground and knocks Meltryllis into the dump. After it's killed, Beckman warns there are only eight hours left before SE.RA.PH reaches the seabed. Ritsuka and Suzuka then use a tow cable provided by EMIYA Alter to lower themselves down into the dump.
Meltryllis awakens to find her legs broke from the fall. Ritsuka and Suzuka then arrive to save her. Suzka protects Meltryllis and Ritsuka from the monsters, but they seem to be innumerable. The trio try to retreat, but they find the cable has been cut. Tristan arrives to save them, but now he's also trapped with them. Meltryllis warns Beckman will self-destruct from his desire if he enters the planetarium. She then realizes they're in the Calf when BB arrives to confirm the Cruel Thenar, Meltryllis's former workplace, is ahead. She prepares to send the group further down into SE.RA.PH, warning it'll reach the seabed in five and a half hours.
Meanwhile at the chapel, EMIYA Alter kills Beckman. He then kills Marble, revealing he needed all Seraphix's staff dead to prevent Animusphere's experiment from being repeated. He prepares to go and destroy the planetarium when a mysterious voice criticizes his ruthless and callous approach. He recognizes the Spirit Origin pattern, and the voice in turn recognizes him. They remind him of the cult he slaughtered, even though the only evil person there was the woman who founded it. They reveal themselves to be that same woman he killed after massacring the other members who tried to protect her. She also reveal she was the once that consumed Gawain, and prepares to kill EMIYA Alter next.
The group are sent to the Cruel Thenar by BB. Meltryllis explains Seraphix was officially used for oil excavation, while secretly being used to investigate Leylines. She then asks Ritsuka to open her Maiden Coaster, knowing they bought the key to it from BB earlier. If defeated in her mindscape, her Karmaphage will also disappear, and the area will be unlocked. Ritsuka opens Meltryllis's Maiden Coaster, and she is eventually defeated. She then transports everyone to the front side in front of the chapel. The group enter the chapel to rest, but they see no signs of Arnold, Marble, or EMIYA Alter. BB then announces SE.RA.PH will soon reach the seabed, and offers the chance to fight her at the planetarium. Ritsuka, Tristan, Cat, Passionlip and Suzuka leave for the planetarium while Meltryllis stays behind.
The group arrive in BB's studio in the planetarium, and fight her. After BB seemingly disappears, the room becomes pitch black, and sound is also muffled. Someone tries to ambush the group, but they fail in their attempt. The group then find BB's studio gone, and discover 128 Coffins with people still inside. They're the Masters who summoned the 128 Servants. EMIYA Alter reveals Seraphix's core is called the Celestial Body Simulator, System Animusphere. It is here Zepar used the Master candidates to summon the 128 Servants. They died long ago, but the Coffins kept their circuits active. The corpses continued to summon 128 Servants until Ritsuka arrived. EMIYA Alter confesses he destroyed the coffin's power source. He then prepares to kill Ritsuka to remove all knowledge of the planetarium's existence. Robin then arrives to help defeat EMIYA Alter. After he's defeated, Marble suddenly appears and reveals herself her true form. She is the therapist, introducing herself as Kiara Sessyoin. She reveals she eventually reconciled with Zepar to try to save the people. She then reveals herself to be Beast III, the Beast of pleasure. She explains SE.RA.PH is shaped like a human body because Zepar transformed Seraphix into her body. She confirms she summoned BB under Zepar's influence. Through Zepar's teaching of parallel world, she eventually learned about another version of herself, who usurped the Moon Cell in the Far Side of the Moon. Impressed by this version of Kiara, Zepar linked the two Kiaras together. Passionlip realizes Zepar used Kiara as a catalyst to give SE.RA.PH form. She reveals Kiara swallowed BB, Meltryllis, and her back in the Moon world. Since Kiara served as the basis of SE.RA.PH, Meltryllis and Passionlip were salvaged from her to become Sentinels. Kiara explains Zepar lacked the means to run SE.RA.PH, so he had to rely on the Alter Egos and BB. Suzuka and Cat attack her with their Noble Phantasms after realizing her monstrosity when SE.RA.PH. cracks the seabed. It will continue to sink until it reaches the Earth's core, and once it arrives, Kiara will become one with the planet. Kiara proclaims this will let her bring salvation to humanity. Before that however, she easily kills everyone except Ritsuka when they try to fight her. She tries to consume Ritsuka, but BB rayshifts them.
It is revealed Zepar used Kiara to effectively gain control of Seraphix. Kiara incited chaos among the staff after he transformed Seraphix into SE.RA.PH. She seduced the personnel to open the planetarium, and BB and the 128 Servants were summoned. She took control and ruled SE.RA.PH from the behind the scenes all the while claiming she was doing it for Zepar. It was at this point Zepar realized that Kiara has overtaken him. Kiara refused to create a Singularity according to Zepar's plan. Regulated to her pinky finger, Zepar was eventually released and quickly faded away. Kiara then ordered BB to start the Grail War to keep her entertained while SE.RA.PH falls.
Ritsuka arrives in an old classroom along with everyone else. BB reveals she reversed time to undo their deaths. She explains a time leap of approximately three hours is possible in the digital world if it's within a Quantum Time-Lock. The right coordinates also needed, which is the purpose of the class room located approximately hundred meters above SE.RA.PH. BB explains further that SE.RA.PH digitized the Mariana Trench as it passed through it. Thus, under these circumstances, the higher they go, the further they go back in time. It is theoretically possible to travel back to the point before Ritsuka's arrival if they return to the surface if they had the right coordinates. The problem though is escaping Kiara's sexual allure, which acts like a gravitational field. BB explains the group needs to exceed the speed of light to escape, and while possible in the digital world, they would be destroyed in the process. She then reveals she was summoned to stop Kiara's plan, and that Kiara forced her to manage SE.RA.PH until now with the Grail War's conclusion. She also reveals Beasts come in pair, and Kiara is becoming the "R" of Beast III. Kiara used SE.RA.PH to become a Beast, but she's also still bound to it. The group then go to fight Kiara to prevent her from fusing with the planet.
The group arrive back at the planetarium. Kiara reveals she became a Beast out of jealousy of the delight she felt from Zepar's memories of the Battle at the Time Temple. After revealing she wishes to worshiped as a god of pleasure, she tries to convert the group into her followers. It is negated however by BB's secret weapon that counteracts the erotic magical energy in SE.RA.PH for the next five minutes. Kiara then fights the group more directly. They defeat her, but the area fades away. SE.RA.PH's gravitational field weakens, so everyone begins to float. SE.RA.PH accelerates, and Demon Gods manifest. Meltryllis points out to Kiara that disabling SE.RA.PH's gravitational field has left it defenseless. At her request, Ritsuka uses their remaining Command Spells to empower her and Passionlip. Meltryllis then has BB transport everyone expect her and Passionlip to safety.
Meanwhile at BB's studio, she warns SE.RA.PH's descent is accelerating, and an innumerable Demon Gods are flowing out from it. She explains that as SE.RA.PH rapidly expands, it will unleash a rain of Demon Gods upon the sea. She lacks the processing power to halt SE.RA.PH's expansion alone. She'll need someone with Moon Cell processing power, so Suzuka offers to help.
It is revealed Meltryllis and Passionlip previously failed to destroy Kiara. After injuring Meltryllis's arms, Kiara killed a different version of Ritsuka as punishment for defying her. She also stopped BB's time leap because a part of her still existing inside of Meltryllis and Passionlip, their Karmaphages. Meltryllis vowed to redo everything, and help Ritsuka instead to free the Sentinels of Kiara's influence. Passionlip uses Virgin Laser - Palladion to launch her upwards at faster than light speed so she can travel back in time. Meltlitlith visits her past self in the chapel, and shares her memories with her. In order to prevent Kiara from realizing the truth, the past Meltryllis committed suicide, leaving only a broken ceramic figure.
Passionlip uses Virgin Laser - Palladion to launch Meltryllis at Kiara. Meltryllis crashes into Kiara, crushing her heart. As her body begins to crumble away, Kiara turns her hair into Demon Gods to grab Meltryllis in an effort to possess her. Her effort is made in vain though when EMIYA Alter destroys the Demon Gods entangling Meltryllis. He then puts a cable around Meltryllis's waist and has her pulled up to safety. Kiara's body soon crumbles away completely.
Ritsuka wakes up in BB's studio. It is revealed Tristan was the one who pulled Meltryllis up. EMIYA Alter disappeared after using the last of his strength to save her. Meltryllis also disappeared because her Spirit Origin was too damaged with a second Virgin Laser - Palladion. However, BB saves her Spirit Core as a cube, so she can be resummoned as a new Heroic Spirit. With the destruction of Kiara, the Servants are released, and BB rayshifts Ritsuka back to Chaldea. They arrive back, but Da Vinic says Seraphix was dismantled at the beginning of the year. BB reveals what transpired was processed as a void phenomenon. She then joins Chaldea to repay Ritsuka for their help.
Later, Ritsuka is sent back to SE.RA.PH by BB to help her save the world. They're contacted by a different version of BB called BB/GO. She reveals she now control SE.RA.PH. She plans to patch it into the internet, and use Earth's factories to mass-produce BBB robots to conquer and imprison humanity. After her robots capture humanity, she'll use their brains as bio-processors, then connect their minds to SE.RA.PH so they can all worship her. She reveals she was salvaged from Kiara, and BB is a copy of the original sent from the Moon. She also reveals she captured Nero, EMIYA, and Tamamo, and turned them into Sentinels. Ritsuka will to need defeat them to unlock the central are where BB/Go is. After BB/GO ends transmission, BB reveals she was sent by the Moon Cell to prevent Kiara's transformation into Beast III. She explains Kiara absorbed her, Meltlilth, and Passionlip during the Moon Grail War. After becoming a god of pleasure, Kiara salvaged them from herself to serve her. Meltryllis and Passionlip, but BB redefined herself as BB/GO, and pretended to be loyal. BB asked BB/GO to manage SE.RA.PH while she hides at its bottom until she regains the strength needed to defeat Kiara. Later, Ritsuka frees Nero, EMIYA, and Tamamo from BB/GO's influence. Everyone then goes to the central area, and defeat BB/GO. After she merges with BB, they all return to Chaldea.
|Alter Ego||Meltlilith||Ritsuka Fujimaru|
|Saber||Nero Cladius||Ritsuka Fujimaru|
|Beast III/R||Kiara Sessyoin||N/A|
- ↑ 1.0 1.1 Fate/Grand Order: Epic of Remnant - SE.RA.PH. - Deep-Sea Cyber-Nirvana, Prologue
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Fate/Grand Order: Epic of Remnant - SE.RA.PH. - Deep-Sea Cyber-Nirvana, Act III: The Nutcracker, Once More
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 Fate/Grand Order: Epic of Remnant - SE.RA.PH. - Deep-Sea Cyber-Nirvana, -Finale-
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 Fate/Grand Order: Epic of Remnant - SE.RA.PH. - Deep-Sea Cyber-Nirvana, Epilogue: Palladion That Tears Through Time
- ↑ 5.0 5.1 Fate/Grand Order: Epic of Remnant - SE.RA.PH. - Deep-Sea Cyber-Nirvana, Bottom Black Encore!
- ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 Fate/Grand Order: Epic of Remnant - SE.RA.PH. - Deep-Sea Cyber-Nirvana, Act I: Swan Lake Returns
- ↑ 7.0 7.1 7.2 7.3 7.4 7.5 Fate/Grand Order: Epic of Remnant - SE.RA.PH. - Deep-Sea Cyber-Nirvana, Act II: Coppélia of Avalanche
- ↑ 8.0 8.1 8.2 8.3 8.4 8.5 Fate/Grand Order: Epic of Remnant - SE.RA.PH. - Deep-Sea Cyber-Nirvana, Act IV: The Sinking Beauty
- ↑ Fate/Grand Order: Epic of Remnant - SE.RA.PH. - Deep-Sea Cyber-Nirvana, One Day, Let's Meet in the Digital Sea