Terraside 2

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* Title screen
* Original title card

**Terraside 2** is the fifth episode of Mainstream, serving as the finale of the Replacer Story Arc.

## Synopsis

> *The time has come to end what has started with the burning question in the back of the mind. Everyone gathers to confront the Replacer Syndicate for their respective purposes.*
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## Appearances

* Coffin Company
	+ Coffin
	+ Administrator
	+ Managerial Department
		- Lee Sooyeon
		- Kim Hana
	+ Operations Department
		- Lena Mackenzie
		- Chloe Starseeker
	+ Fenrir Squad
		- Yoo Mina
		- Hilde
		- Joo Shiyoon
	+ ALT Squad
		- Eujin
		- Xiao Lin
		- Kim Sobin
* Replacer Syndicate
	+ Replacer King
	+ Replacer Queen
	+ Regenerated Bishop
	+ Replacer Bishop (Mentioned only)
	+ Regenerated Knight
	+ Replacer Knight (Mentioned only)
	+ Replacer Rook
	+ Seo Yoon
	+ Replacer Warden
	+ New Ohio
* Ian Mason
* Mason Mercenary Office
	+ John Mason
	+ Tommy and the Losers
	+ Zhang Wei
* R7 Irregular Scouts
	+ Orca
	+ Shadow Orca
	+ Charlie Rockwood
	+ Jessica Green
* Jane Doe
* Freedom Riders
	+ Lee Minseo
	+ Hirose Aki
* Delta Seven
	+ Maria Antonov
	+ Jake Walker
	+ Kyle Wong
* Unidentified Eternium Scammer
* Elixir (Mentioned only)
* Drop Ship
* Six Wings
	+ Na Yubin
	+ Lee Jisoo
	+ Amy Firstwing
* The Militia
	+ Lee Yuri (Mentioned only)
* Demon Lords
	+ Asmodeus
	+ Nehemoth (Mentioned only)
* Corrupted Objects
	+ Nameless One (Mentioned only)
* Nameless One's World (Mentioned only)
	+ Dominic Reginald (Mentioned only)
* Grand Purification War (Mentioned only)
	+ Battle of the North Pole (Mentioned only)

## Plot

### Act 1

The episode begins with Mina, Shiyoon, SWAT 4, and John Mason watching a recording left behind by Ian Mason, John's brother who officially died in a traffic accident. In the video, Ian recounts how he joined the Replacers— several years ago, he met a man named "Mr. Reginald" at a bar who recruited him to work on Project Terraside. Things initially went well until Ian accidentally saw the Replacers experiment on a human; instead of making the Counterside habitable as Ian originally thought, the Replacers were actually turning people into mindless Replacer hybriders.

Ian explains that the Replacers needed an Immortal System Core to make Project Terraside a reality, but lacked the resources needed to acquire one. However, the Six Wings provided an Immortal System Core to the Replacers, and Ian decided he would try to destroy the Core himself. In the event of his failure, he further explains that he split Plan B into three sets of dummy data and placed one in Jane Doe's email, another in the Replacer VPN network, and another in a VeriChip in one of the officers.

After the recording ends, John tells the others that Jane Doe is a former liasion of Ian's who was likely originally hired by the Replacers to keep an eye on him— she is currently safe and recovering elsewhere after being injured whilst escaping a Replacer base. Furthermore, John has determined that Ian's plan provides a method to track the New Ohio via the Immortal System Core's signals and has a code that will temporarily shut down the New Ohio's dimension jump system. However, to put Ian's plan into action, approximately a little less than a hundred kilograms of pure Eternium will be requiredto track the New Ohio. SWAT 4 is shocked at the amount, stating it half a year's budget, but John assures them that he knows where enough Eternium can be found.

While the group are driving a Lost Ship Disaster Area, Mina asks John if they could just ask Delta Seven for the Eternium, but John replies that the price of Eternium has skyrocketed while Eternium mining has halted completely due to the Lost Ships and Corruption Syndrome outbreaks. Eventually, the group encounters the R7 Irregular Scouts and help them hold off some Corrupted Objects. Afterwards, John convinces Jessica that he was a friend of Eddie's and asks for the Eternium stash they found on their last mission. Jessica says that Charlie was scammed out of the Eternium, and the scammer is located inside another disaster area.

As the group leaves to find the scammer, Mina tries some of Orca's marshmallows. They find a giant cocoon in their path, and John suspects that it holds a strong Category 3 or Category 4 C.O. After dealing with the C.O.s guarding the cocoon, the group continues on their trek. Eventually, they are stopped by the Freedom Riders, who recognize Mina and explain that they were hired by scammer to protect a nearby Eternium storehouse. The scammer comes outside to yell at the Freedom Riders but is interrupted by John, who accuses the scammer of deceiving Charlie into giving him the Eternium through an illegimate deal. Soyoung backs up John and says that fraudulence makes the contract void, but the scammer still refuses to hand over the Eternium. John instead makes a new deal: he and his team will protect the scammer from the C.O. in the cocoon in exchange for all the Eternium he has. The scammer reluctantly agrees and tells John that the Eternium is loaded in a truck (which he also stole from Charlie) nearby.

As the group fends off C.O.s, the scammer attempts to flee in the truck but is killed by the cocoon. John decides that the group must fight the cocoon while it is still weak in order to reclaim the Eternium. After the C.O. is taken down, the Scouts decide they will join the group in their fight against the Replacers. The Freedom Riders are afraid to come along but are convinced to do so when Mina claims they'll end up being drafted by the Administration into taking down the Lost Ships instead.

### Act 2

John drives the group to a safe house, where Mark Finley, Jane Doe, Tommy and the Losers, and Zhang Wei are waiting. Jane, fully healed, says she can help against the Replacers due to her in-depth knowledge of the organization. John also reports he has the Eternium to Mark, and Mark says he enlisted the rest of ALT Squad's help to neutralize Seo Yoon. ALT Squad enters and asks Mina about their former captain, but Mina affirms that Yoon is a traitor.

John then goes over their objectives: locate and intercept the New Ohio, which they'll do by eliminating simultaneously the Replacers' four Abominations designed to amplify dimension interference waves; disable its dimensional jump and stealth system; and call the Administration TASKFORCE fleet to eliminate the Replacers. With the Coffin out of action, Mark provides the Drop Ship to the group so they can dive into the Counterside and destroy the Abominations. He notes that the Drop Ship can't bring them back to Normalside but assures them that they should be able to return in one of the Administration's ships. John divides the group into four teams— ALT Squad, Orca's team, SWAT 4 and the Freedom Riders, and finally Fenrir Squad and John's own team.

After ALT Squad destroys Abomination Alpha, Eujin wonders if Yoon truly abandoned them while Xiao Lin asks her if she has the resolve to fight their former captain.

SWAT 4 and the Freedom Riders find Abomination Beta. They also find encounter a Shadow and get it and the Abomination to fight and weakenen each other, allowing the group to defeat the winner. Soyoung suggests collecting whatever the Shadow dropped so she can ID it later. When Yumi offers to do it herself despite her physical stress, Soyoung tells her to relax as she knows Yumi is worried for her missing sister— she says she'll tell Yumi everything after they get back.

While Orca's group make their way to Abomination Gamma, Charlie worries that Orca will go beserk again now that they're in the Counterside. Orca assures him that she is in control of herself. The group find their target along with a Replacer Captain, who uses the Suppression Protocol to ready the hybriders at his disposal for a fight. Orca kills the Abomination and force the Replacers to retreat to the last sremaining Abomination before collapsing from exhaustion. As Charlie rushes over to help, Orca snacks on some marshmallows.

Fenrir Squad and John's team arrive at Abomination Delta at the same time as a Replacer fleet. Seeing the high number of troops guarding the Abomination, Jane and Tommy's group lure troops away. Shiyoon offers to help Mina use a small portion of her Qliphoth Factor to deal with the remaining Replacers. At Shiyoon's request, Mina shows him the blade in her gun, which he grabs and powers up with his blood. The two of them go off to fight the Replacers.

After destroying Abomination Gamma, Mina says that using the Qliphoth Factor hurt, and Shiyoon says that the pain will go away in a short time. He explains that he can also use the Qliphoth Factor due to his parents, though they called it Dragon Blood. He pledges that he will continue to help Mina however he can as she is critical to finding out why his parents were killed for using Qliphoth Factor. With all Abominiations neutralized, John uses the Eternium acquired from earlier to detonate the Drop Ship's Implosion Reactor, allowing the group to reach the New Ohio's location. He then sends out the dive coordinates to the other teams so they can join the fight later.

### Act 3

Regenerated Bishop talks with Replacer Queen while listening to Auld Lang Syne on a radio outside the New Ohio's stealth field. Queen is surprised that Bishop's radio could pick up anything and wonders if there is a radio station nearby. Bishop says the song was used in the original Bishop's graduation ceremony and feels nostalgic by it, but Queen says she shouldn't think much of it since Bishop is merely a copy of the original. Queen stresses how important Bishop is to Project Terraside and argues that Bishop can fulfill her source's desires by completing it.

The Drop Ship breaks apart midair as it dives to its location, separating its occupants from each other. Mina and Shiyoon land together, but the latter is found and taken away by an unseen figure. The figure says goodbye to a groggy Mina, who finds her voice familiar but is unable to recognize it. While trying to find Shiyoon and the others, Mina runs into a Replacer patrol squadron that is already engaging with ALT Squad. After they defeat the Replacers, Mina and ALT Squad are confronted by Yoon, who brings along another Replacer squadron. The Replacer Warden tells Yoon that he expects her to eliminate ALT Squad and Mina if her loyalty is to be trusted. Mina gives Yoon one final chance to come back to her side before engaging her in combat. When Mina and her Qliphoth Factor becomes too much for Yoon to handle, the Replacer Warden unlocks the Misteltein for Yoon, allowing her to defeat ALT Squad and Mina. As Yoon prepares to execute Mina, she suddenly turns her weapons towards the Warden and fires, killing him. The other replacers attack Yoon and everyone else in response but are all killed as well.

Yoon reveals that she has been a double agent for Coffin Company all along and as proof shows them a holographic recording of the Machine G.A.P. explaining Yoon's (and, by extension, the rest of the group's) true objective: search and destroy the Replacer Syndicate's weakness from the inside. Yoon explains they must destroy the Regenerated Bishop, who serves as the Arbiter controlling the Immortal System Core. She also warns that the mere appearance of Queen will cause the operation to fail due to her immense power. Yoon also adds that she met Queen before as a child and was placed her inside an Extractor by her, but the chaos of Ian Mason's rebellion allowed her, along with the rest of ALT Squad, to escape.

When the group encounters Bishop, Bishop confirms that only she and Replacer Rook can control the Immortal System Core, but Rook is currently in cryopreservation and would be unable to handle the necessary calculations. After Bishop is defeated, Mina decides to spare Bishop as she wants to give her a chance to follow her own will. Enraged, Yoon tries to kill Bishop herself, but Queen arrives to rescue Bishop. Before Queen can subdue them, she gets a call from the New Ohio that the ship's Eternium drive, quantum coordinate operator, and stealth field are disabled, forcing the Replacers to retreat to the ship. The group see that the Administration has sent their fleet to help, including a repaired Coffin.

Elsewhere, Shiyoon meets with the Six Wings. Na Yubin confronts Shiyoon over his Dragon Blood and offers to assist him in awakening it. Shiyoon refuses even after Yubin additionally offers to tell him the reason Hilde killed his parents. Yubin says Shiyoon is looking for a reason to forgive Hilde. Shiyoon attempts to leave, but Yubin stops and battle him, hoping that putting Shiyoon in great danger will awaken him regardless.

### Act 4

John, Jane, and Tommy and the Losers get together after the Drop Ship crash and decide to search for the other teams. John takes the marshmallows Tommy has and sets them on fire to attract Orca. The R7 Irregular Scouts arrive, but the fire also attracts Replacer collapser. After the combined group neutralizes the threat, John finds handcuffs on one of the collapser bodies, leading him to believe SWAT 4 may be held prisoner at a nearby Replacer encampment.

SWAT 4 is in fact captured and escorted in a truck by a group of Replacers because Yumi refused to run away while the Freedom Riders did. Yumi complains about their situation and tells Soyoung to stop throwing things outside the vehicle they're in, but Soyoung says it's part of her escape plan— the Freedom Riders have been following the trail Soyoung is leaving behind, hoping to save the police officers. Eventually, the Freedom Riders catch up up but are quickly attacked by the Replacers. Jane goes to rescue the officers while John helps the Freedom Riders fight back. Once the officers are freed, John decides the group's next move is to find the New Ohio and disable its stealth field.

Before the group move out, though, the Replacer Pawn arrives and states his intention to kill Orca for destroying his original body. Pawn splits into multiple beings, and Orca tells the others to run ahead to the New Ohio while the Scouts keep Pawn's attention. The splitters then combine to form the Replacer Pawn polymer. Inside Orca's Shadow Palace, the Orca tells Orca that she will likely die here, so Orca allows it to take control of her body for some time to fight Replacer Pawn.

Meanwhile, John driving his team in a captured Replacer vehicle and reaches the perimeter of the New Ohio. They see Queen in the area, but she flies away as they approach when the Regenerated Knight appears before them. Yumi demands Knight to surrender, getting her attention, while she tells John and the rest of the group to reach the New Ohio. Jane uses the backdoor key to disable the New Ohio using an external console, shutting down the ship's stealth field. John confirms to Mark that they've succeeded in exposing the New Ohio, so Mark activates Freedom Strike to call in the Administration fleet.

Inside the New Ohio, Replacer King reviews the situation. He asks what happened to Yoon, and Queen answers Yoon was given the original Misteltein before her betrayal. King says that means the Replacer contingency plan is complete and tells Queen that this will likely be the last time he sees her.

On the Delta Seven flagship USSA New Enterprise, Kyle Wong and Lieutenant General Maria Antonov sends out a broadcast to the Replacers and demands they surrender. King responds to Maria that he's doing this for all of mankind, but Maria ignores this and says she'll give him a peaceful death for being a traitor. The New Ohio tries to use the Immortal System Core to destroy the Enterprise, but the Enterprise uses its Gamma Ray Buster with its Black hole drive to ground the New Ohio. Delta Seven then leaves the ship to assault the New Ohio.

### Act 5

Delta Seven encounters Regenerated Knight and defeats her, with Jake landing the finishing blow. However, Sylvia notices that the Replacer Factors composing Knight are regenerating. Queen arrives with Pawn, who apologizes for attempting to usurp Queen. Maria recognizes Queen as Jaine Kropel and reveals to the rest of Delta Seven that Kropel is formerly a colleague of her's and Dominic's who participated in black operations during the Grand Purification War— she was believed to have died after the Battle of the North Pole. Knight regenerates, and Queen explains that the Immortal System Core will continue regenerating Replacers indefinitely, including herself.

Elsewhere, Shadow Orca is disappointed that Queen took Pawn away and orders Charlie to take care of Orca's body so Shadow Orca can regain strength for her next return. Shadow Orca then passes out, allowing Orca to regain control of her body. John's group, the Freedom Riders, and SWAT 4 then link up with Orca's group. Yumi mentions that all the Replacers vanished and suspects it has something to do with Replacer Queen. as well as the appearance of the Enterprise. The combined group then finds Mina and ALT Squad, who explain that Yoon was a mole and is still on their side. They soon hear the battle between Delta Seven and Replacer Queen.

Jake reports that Knight has died seven times thus far, and Maria suspects that Knight's mind is gradually fading the more she regenerates. Maria orders Kyle to distract Knight and orders Jake to focus on Queen. Queen shows that she can regenerate multiple Knights by converting her surplus of Replacer Factors into Regenerative Progressive Factors. The Drop Ship arrive and join Delta Seven in their battle against Queen. After a while, Queen announces that she has absorbed enough energy due to the repeated deaths of the regenerated Replacers and forms a halo over her head. Queen explains that the the Eternium crystal of the Nameless One was used as the original Replacer Factor and that the Nameless One itself has regenerated as her halo. When Kyle asks what the Nameless One is, Maria answers it is Category 5 C.O. she describes as "immortal" that appeared near the end of Grand Purification War. It was too powerful to defeat, but Jaina had sacrificed herself to drive the C.O. away to the farthest depths of the Counterside. Queen further reveals that, after taking the Nameless One away, she and Dominic studied the C.O., which was near its death, and later reproduced its body.

Elsewhere, Yubin decides to let Shiyoon leave as his real goal was to increase the global corruption rate by increasing the amount of active Qliphoth Factors active in the world. He also realizes that Hilde has arrived and plans to activate her own Qliphoth Factor.

On the Coffin, Lee Sooyeon asks Hilde if she is sure about using the Qliphoth Factor. Hilde says she has no choice as the situation will only get worse if she continues to hold back and allow the Replacers to mass reproduce Qliphoth Replica Factors. Hilde orders the ramp door to open and leaves. Sooyeon talks to the Administrator, thinking all his plans were ruined, but the Administrator says that everything is going to plan thus far. He notes he is impressed that Mina spared Bishop and ended the chain of hate. Sooyeon says that, since Hilde intends to activate her Qliphoth Factor, the Game is sure to begin.

Maria considers using running the Enterprise's black hole drive to force Queen back into the hyperdepths of the Counterside like she did in North Pole Operation, but Queen counters this by making multiple copies of herself. Hilde soon drops nearby joins the fight against Queen, activating her Qliphoth Factor. Delta Seven watch Hilde fight Queen, commenting that Queen can barely stand after enduring Hilde's attacks. As Queen regenerates, Hilde orders Mina to enter the New Ohio and destroy the Immortal System Core to stop the regeneration.

Inside the New Ohio, Shiyoon opens a log about Project Terraside and deletes it. Mina finds him and notes that the ship is devoid of any crew. They go to the Engine Room where Shiyoon believes the Immortal System Core is housed, finding Replacer King and Regenerated Bishop waiting. Impressed by their endurance, King welcomes Shiyoon and Mina aboard, but this only infuriates Mina. King says he does not regret what he has done to get to this point as his goal is to save mankind for the end of the world. He explains that the Counterside consists of past worlds that were destroyed, and his solution to the "Counterization", i.e. the end of the world, was turn everyone into Replacers so they can survive in the Counterside; these people would be C.O.s capable of reason like the Nameless One. Replacer and Alternative Factors would have been used to turn people into Replacers, but King decided to focus on copying the Qliphoth Factors instead so that the Nameless One's Eternium core could be reproduced. But as Qliphoth Replica Factors require far more resources to produce than Replacer Factors, the vast majority of the current world's population would have to be sacrificed for its production. With that information, Shiyoon figures out that the New Ohio's crew were used to produce them. Bishop reports that the distribution of Qliphoth Replica Factors is almost ready, and Shiyoon mentions that the aftermath of a distribution would be cataclysmic as they are many people infected by Replacer Factors. King makes an offer to Mina to join him, but she refuses, so he constructs Replacer hybriders to attack her and Shiyoon.

As he endures the assault, Shiyoon says that they should attack Bishop as she is critical to the production and distribution of the Qliphoth Replica Factors. He also realizes that King is fused with the Immortal System Core, allowing him to extract and use Qliphoth Factors from Mina. When Mina hesitates to kill Bishop, Shiyoon reveals to her that it was Hilde who killed his parents who using the Dragon Blood; Hilde had been going after carriers of Qliphoth Factors but spared both Shiyoon and Mina, and Shiyoon has been wanting to know why. He urges Mina to be honest with herself and let go of Shin Narae as he continues to fight back King. Eventually, Shiyoon damages the Immortal Core Sytem and stop its regeneration mechanism. He then asks King if he plans to be the leader of a world with Replacers, noting that he's still human, but King says he does not as it would cause him too much guilt. Mina still refuses to kill Bishop as she doesn't want to lose herself doing so.

Queen runs away from Hilde, and Hilde notes that the Replacers stopped regenerating, resulting in the final deaths of Knight and Pawn. A mystery girl known as Asmodeus appears in front of Hilde and mocks her for putting in considerable effort against Queen. She says that if Hilde had used all her power, she would have quickly defeated the Replacers but also awaken all the Demon Lords. Hilde asks how many Demons Lords are awake, but Asmodeus answers at least she and the False Savior are. Asmodeus then bids Hilde farewell and says they'll meet in person during the Game starts. Maria thanks Hilde for her help while Sylvia questions how the Coffin Company commander has so much power. Sooyeon appears and claims Hilde was field testing out a prototype Tech Level 5 gear on behalf of the Administration— the blueprints for said gear will later be distributed to each TASKFORCE company.

Back on the New Ohio, Bishop questions Mina's decision to spare her again, and Mina answers she believes Bishop will not go through with Project Terraside even if she is not Narae. King asserts that Bishop will distribute the Replica Factors no matter what since the original Bishop hated the world, but Bishop refutes this and says meeting Mina allowed her to understand how her source truly felt— Narae never had the courage to truly desire the destruction of world. Bishop aborts the distribution and begins dismantling the Replacer Replica Factor instead, shutting down System Terraside. As she begins to disintegrate since the System is integrated within her body, Bishop tells Mina that she is the only person in the world that's special to her before completely disappearing. A mortally injured Queen then enters and urges King to escape, but King thinks the Replacers are doomed now that System Terraside is no more. Queen argues King can resume his plan if Rook is awakened to fix the Immortal System Core, and so King reluctantly uses an emergency escape quantum tunnel to leave.

Before she goes after King, Mina asks Shiyoon what he thinks of Bishop's last words to her. Shiyoon suggests Bishop saw Narae as her mother for being her source, and Mina was Bishop's only living connection to what she considered family. Mina proceeds to chase after King while Shiyoon holds off Queen.

Mina ends up in a Shadow Palace and finds King, who plans to kill her and takes her Qliphoth Factor so he can use it in conjunction with Rook and the Immortal System Core. He then uses the Immortal System Core to turn himself into a Replacer and summons illusions of his Replacer officers to fight Mina. Mina summons illusions herself and defeats King. The Immortal System Core is now damaged beyond repair, but King assures Mina that Project Terraside will be restarted by someone else and states the plan has been in the making long before him. Mina leaves King behind before the quantum escape tunnel collapses and dumps everyone into imaginary space.

Mina wakes up on the Coffin where Shiyoon explains that the New Ohio, presumably along with the Replacer Factors, was swept away by the blast caused by the collapse of the quantum tunnel, while the spread of Corruption Syndrome has stopped. John's team, ALT Squad, SWAT 4, the Freedom Riders, and the Irregular Scouts are also onboard. Charlie asks Kim Hana if the Scouts can join Coffin Company, and Machine G.A.P. accepts. Machine G.A.P. then invites the entire Coffin Company to a dinner as a reward for taking down the Replacer Syndicate, though he will be late himself as he needs to interview a new recruit.

Some time later, Mina visits Narae's grave to pay her respects.

Maria is seen reviewing data recovered from the New Ohio before it was lost. According to one of the logs, the previous world not only lacked enough Replacer Mutation Factor to transform someone into a Category 5 C.O. but also failed to secure Corruption Frenzy resistance to last until the spacetime abortion was over. Because of this, a test subject, named Maria Antonov, was sent to another world as a sample for a new Replacer Factor. Elsewhere, the Administrator unfreezes Replacer Rook and asks if she is hungry. Rook says she is, so the Administrator brings her to Coffin Company, where she can eat and sleep as much as she likes.

## Gallery

Ian Mason explains his history in the ReplacersJohn talks about the astronomical price of EterniumJohn discusses the plan to kill the AbominationsJohn discusses the plan to kill the AbominationsJohn discusses the plan to kill the AbominationsMark unveils the Drop ShipShiyoon uses his Dragon powersAmy and Shiyoon watch Mina after the Drop Ship crashYoon has Misteltein unlocked for her fight with MinaYoon prepares to execute MinaYubin prepares to fight ShiyoonShiyoon defends himselfShadow Orca takes overMaria orders the Replacers to surrenderEnterprise fires its black hole drive.The New Ohio is hitDelta Seven is deployed.The Enterprise on standbyQueen shows the Nameless One's new formMaria talks about the Nameless OneDrawings related to the Qliphoth GameSooyeon asks Hilde is she's sure about using Qliphoth FactorSooyeon watches Hilde drop from the CoffinHilde activates her Qliphoth FactorBishop dies destroying System TerrasideQueen attempts to rescue KingShiyoon tells Mina to pursue KingReplacer King is defeated.Replacer King is sent to imaginary spaceMaria reviews the New Ohio's logsThe Administrator awakens Rook from cryostasis