An email from Dr. Ritsuko Akagi, sent to Major Katsuragi

How low are the odds you'll see this, I wonder? Even if you do, it will likely be after the information could help prevent something awful. Yet, this is the only way I know to safely inform you of what's happening.

I'm sure you're dubious of Nephilim's current situation. On its face, the Commander accepted an ultimatum, seemingly without argument. That hardly seems like him. The man's never been content in his life, but a semi-interdimensional clone made him give up his daughter? You know something is amiss.

Our Commander maintains some secrets, but I will reveal what I can. In doing so, I hope you can recognize my apology. There will be no request for forgiveness, from you or anyone else. As I type this, my only regret is that I wounded a dear friend. You're worth more than that.

Consider the following timeline:

It began the day of the Entry Plug incident with Zenitsu. While all of us turned our attention to the young man's safety, certain analytics went unnoticed. The Evangelion reacted to him.

We should have guessed something like this would be the case. From the beginning, the Slayers spoke of a heightened sense of "feeling". They have a sensitivity to intent and emotion that nobody in Nerv ever considered possible. On that first day, Inosuke felt something from the Eva. The Eva can respond in turn.

I didn't understand what this meant until Rei began taking blood samples. She requested to have some of Zenitsu's blood injected into her system. She even had a cogent argument. We understand the Evas by our relationship with them. We understand the Angels by their relationship with us. We don't know to what the Slayers relate, so she volunteered to be that experiment. She stressed the point that she was "replaceable".

I agreed to help in the experiment.

There's one thing you should know about the Slayers' blood: it separates from LCL fluid. That's why they cannot breathe it even when its oxygenated. So, what happens when a small amount of this Slayer blood enters the bloodstream of a human from our Japan? Further, what happens when this person is Ayanami Rei, who's DNA contains traces of Evangelion and Angel?

The result is a record-breaking pilot. In the battle on the coast, Rei gave us data we'd never anticipated. Not only did she surpass prior synchronization rates, but her harmonics began to blend with that of the Eva. I briefly feared that Unit-00 was attempting to dissolve her into itself, or that the Slayer blood sample interfered with data collection, but both of these turned out to be wrong.

Rei controlled the Angel. That's the simplest way to explain it, as bizarre as it sounds. As she fought, Unit-00 ceased to reject her. Her thought patterns became the thoughts of the Evangelion. Later, she told me that she felt as if she were seeing from the Evangelion's perspective, that its hands were her hands. Somehow, that mix of DNA within her, when mixed with LCL fluid and adrenaline, caused a reaction.

This would also explain why Rei seemed to change so dramatically after Zenitsu's attack. When the adrenaline began to flow, the mix of elements in her system responded. I can't imagine how dramatically this affected her. The sudden influx of brain activity may have been traumatic in itself.

I digress. I have nothing but time as I wait in Nephilim's chamber.

To the point: imagine how Gendo would react to this data. He discovered that his precious experiment had become a truly superb pilot. Imagine, now, how he would feel about the change to her mental state. His most precious experiment had achieved her greatest state because of outside influences. The more she drifted from his control, the stronger she became.

These results ignited intensified our curiosity. The commander and I both sought to find a means to use this to our advantage. The Slayers changed the timeline. If we could use them to our advantage, there was no question we would do so.

Gendo, I've since discovered, had his own plan.

The next wave of tests began when you took the Slayers and Shinji to meet Asuka. I injected a sample of Zenitsu's blood into a Rei clone. The Commander insisted that this clone be separate from the others. So, I agreed. Immediately, there was an effect. The submergence in LCL fluid caused a blitz of mental activity. The clone soon died.

Gendo, to my surprise, went further back in the Ayanami experiments. He carved more than an hour from his schedule to work on the problem. Rather than injecting it into a pre-existing clone, he wished to form a new organism with the Slayer sample present in its conception. I don't know how much sleep he sacrificed in this time. Soon, though, a new organism began to grow in the womb of the LCL chamber.

It should have taken weeks, or perhaps even months, for a clone to grow. Nephilim became as you see in under forty-eight hours. Inosuke might have seen Nephilim open their eyes for the first time.

By now, you must be asking the same question that plagued me: why?

The Commander only ever responded vaguely, "I'm testing a theory." Only once did he offer something closer to the truth. "We have no time," he stated bluntly. "The schedule has been pushed forward. SEELE threatens to not only disown us, but to attack us outright. We need to hasten Instrumentality. I think I've found a way."

One detail remains. He had a private meeting with Nephilim. After the three of us confronted Nephilim, Gendo returned while you were on the surface. He had me leave the room. I don't know what they discussed.

Misato, I have no regrets in working toward Instrumentality. I do not regret working for Nerv. I am proud to have helped create the Evangelion, and to have played a part in the war against the Angels. My only mistake was that I trusted a narcissist. I ignored his methods because of our shared goal. For that, I am sorry. He believes that failure isn't a viable option. He considers the destruction of the planet to be on par with failing to achieve Instrumentality.

I think he'll do something terrible. Whatever happens, Misato, stop Gendo. I don't care how.

Zenitsu

"Stupid Nerv. Of course, the guy with the broken foot has to go and fix the problems these people made. They couldn't just accept things. No, we can't agree to fight the monsters. We have to fight each other, too. Why?"

He hobbled along, trying to ignore the rumblings of the distant battle. "Guess the pilots are having some trouble up there. Wouldn't that be something, I go down and handle whatever Gendo's done, but an Angel beats us. How ridiculous would that be? Oh, who could've guessed that dividing resources and ruining alliances would make warfare difficult? What's so hard about, 'monsters are attacking; let's work together'?"

So long as he talked, he didn't get lost in his head. If he let himself stop and think, he might start wondering why he ought to bother in any of this.

As he approached the corridor with the elevator, strange noises began to sound. Soft, wet plops of footsteps, murmured laughter. Zenitsu recognized the voice. It made him shudder.

"Well…" Zenitsu whispered to himself, "guess the copies are free. And they can move as fast as me, apparently. Oh, joy. This is… this is… a terrible idea. I hate this. I hate this so much. I smell LCL fluid. I want to vomit."

He sighed, shut his eyes, and inhaled deeply. His hand found a comfortable perch on the hilt of his katana. An odd thought occurred: whatever appeared around the corner, he wouldn't tell anyone about it. He'd ravenously collected every scrap of information he could find of this world, just as he'd scrounged for everything he could learn from the Demon Slayer Corps' history, but he knew that the following events would be best forgotten.

With one more deep breath, he stepped into the hall. Blood dripped onto the once sterile grey floors. Puddles formed around the steps of the empty-eyed clones. Flecks of LCL fluid splashed onto the white walls. Eight clones of Rei stumbled forward, naked and dripping the awful blood-scented substance. The orange liquid matted their blue hair to their heads. A few of them had hair plastered against their retinas. Their bodies showed fresh cuts, random and hectic, as if they fell onto a pile of sharp objects.

Dark and orange mixed together, forming rivulets that streamed down their bodies and through the hall.

The imitations of Rei gaped at Zenitsu. A few of them chuckled, vacant smiles widening. Another raised a hand which clutched a broken bit of glass. Her hand bled around the weapon.

"Well, then," Zenitsu fell into a fighting stance.

Not too long ago, he might have fled from the sight. After all, these copies were both inhuman and inhumane. Now, however, adrenaline coursed through him with a furious zeal. They'd insulted Rei. After everything that poor girl had gone through, she now had this insult against her image. Nephilim had sent out these empty shells. Each clone existed as a killing intent on legs, lacking anything identifiable as human.

If they spread throughout Nerv, many would associate these nightmarish dolls with the name Ayanami Rei. That'd be too awful. Zenitsu could not forgive the monstrous nature of the act.

The red eyes narrowed. The sopping hair twitched upward. Fresh crackles of electricity drowned out the laughter.

"Of course…" Zenitsu tightened his grip. They had defiled her image with his ability. The greatest sin he'd committed in this Japan had been immortalized. Well, it wouldn't go uncontested. If Zenitsu could not apologize to the girl, he would ensure that these distortions of her image would never see daylight.

His own hair fluttered. The lights above him blew out. "Thunder breathing: First Form."

Several clones pounced forward in a flash of light. Simultaneously, a bolt of lightning drove through the crowd. Just as his blade cut through the last in the row, Zenitsu turned and slashed again. They fell, but the laughter persisted. The inhuman creatures writhed, weakly flailing their bits of glass.

Zenitsu moved his blade. Soon, his orange cloak had become red. There'd be others, he knew. Droplets of the awful substance bounced onto him. As he rushed through the crowd, his eyes stung from the stink of LCL. His muscles felt heavier once he stood above his defeated foes.

Before he could relax, the elevator dinged at the end of the hall. He turned to see it open to a fresh group of dolls. They could only come from the lower floors via the elevator, he knew. Was he somehow lucky enough that he'd slayed all the first wave, and that no others had stopped on other floors? This floor had the easiest access to the observation room. Maybe that was Nephilim's plan.

But what kind of tactician would bottleneck all of their troops?

The clones burst from the elevator in bursts of lightning. Steel met glass, then flesh. Zenitsu tried to keep his eyes shut as his body moved. The air recoiled around them, as if repulsed. He found no issue sensing them without vision. So, he dealt with the second onslaught. Hacking and slashing at the face of the girl he'd wronged, attacking until he no longer heard her laughter.

When all became silent, he stood amidst the remains. He gripped his katana so tightly that it hurt. His stomach churned. The LCL which had landed on his skin burned. He wiped away at his cloak, trying to remove as much as he could. It didn't help. The fumes made him feel heavy.

Bile rose in his throat. He swallowed it, forcing himself to stay some degree of composed as he hobbled to the elevator doors. Without thought, he gripped the space between and pulled them open. Immediately, he saw the cable descending. In all likelihood, more dolls were rising toward him.

"I'm a member of the Demon Slayer Corps." Zenitsu said as sheathed his blade. "I've been through many hells before this, and I'll probably see more after." He leaped to the cable, then began shimmying down by hopping from one to another. He needed to focus on every step of the process. His hands felt slick with blood and LCL. "I helped save one world. I can help save another."

His vision seemed to tremble. It wasn't fair. None of it was fair. Zenitsu should never have been brought to this world. He didn't want to return home only to tell Nezuko that her brother had died, not after everything.

"No," he muttered. "I've got this."

As he gingerly landed on top of the elevator car, he realized something: he wasn't a hero. Zenitsu was the coward who'd depended on others to save him. Tanjiro and the Corps had always saved the day. Even Inosuke fulfilled the support role better than Zenitsu did.

Well, Tanjiro wasn't here now. Inosuke would be a while. A threat lay beneath him. Who would protect him if he returned to his home? Nezuko? Did she deserve a coward who couldn't defend himself? No, he wanted to be her equal, her fellow Slayer, someone who would share memories and experiences with her.

Zenitsu broke through the vent into the car. Glass, cackles, and blood greeted him. Electricity danced in the small space.

"Gendo," Zenitsu said once he stood alone amidst the blood. "I will kill you."

Inosuke

The self-taught warrior scrambled to follow the pale Tanjiro. The Slayer of Muzan moved with impossible speed. His red eyes darted about in tiny movements constantly. His feet hardly seemed to touch the ground as they sprinted.

When the explosions rocked the earth, Inosuke's feet faltered. He staggered, swinging his arms in wide arcs to balance himself. Nothing slowed Tanjiro. He charged in an unwavering line, his head hardly seeming to move as he ran.

"Oi! Shouldn't we check that out?" Inosuke yelled as they moved to the nearest entrance to Nerv. When the boar looked over, he saw the Angel. A reverse rain of orange lights shot up toward the Angel. Must have been those rifle things Shinji and Misato talked about. They didn't do anything to the Angel.

He focused on the beast in the air. Compared to the energy from the Angel that had swallowed the hospital, this one's energy hit different. Instead of a ravenous hunger, Inosuke felt as if a living storm bore down on them. He might have felt the same if a typhoon were about to batter the coast.

Suddenly, a red beam shot from the Angel's mouth. The explosion, with the crunching of earth and shattering of metal, nearly deafened him. "We need to help them," Inosuke said, stating a fact.

"We can't worry about that now. Trust Shinji and Asuka. We need to get to Lilith now."

"Why?"

Tanjiro looked over his shoulder. In the middle of running, after all that'd happened, the guy smiled. The red eyes and pale skin made it a bit strange, but still, this determined face was how Tanjiro was supposed to look. "We can trust our allies, Inosuke. They have their task. We have ours."

For the first time, Inosuke felt out of his depth. The person in front of him was Tanjiro. But it wasn't just Tanjiro. This was an Angel attack, but it wouldn't be the last.

Suddenly, he noticed something in the corner of his eye. A little girl stood amidst the carnage. A civilian? Inosuke wondered. A moment later, he recognized her. The kid version of Asuka stood alone, in the direction of the battle.

"You go ahead," Inosuke yelled. "I got my own task."

"Okay!" Tanjiro's wings reappeared. With a sudden burst of speed, he flew off.

Inosuke stared after him. "Oi… just tell me if I'm slowing you down…"

The Angel fired again. The shockwaves brought him back. The kid Asuka tapped her foot in the distance. "I'm hurrying!" Inosuke yelled as he rushed toward her.

Zenitsu

The elevator car had felt like a sauna. The thunder warrior nearly passed out as he existed the way he entered. He'd climb down by hand, as soon as he caught his breath. The fumes made him lightheaded. The world spun and divided in sickening turns. "Gotta move," he muttered. "Move, move. Gendo gonna die today."

Soon, he forced himself to descend one of the elevator cables. Red and orange dripped from his cloak. He tried not to think about it.

On the way down, Zenitsu checked the room where Nephilim – and Rei, he supposed – had been born. Shattered glass floated through pools diluted with blood. The only body in the room was that of Ritsuko. As soon as Zenitsu saw this mess, he gagged and turned away. He'd never liked Dr. Akagi, but nobody deserved that. Being left alone amidst the swirling puddle seemed too awful a punishment. Maybe Gendo deserved it.

With effort, Zenitsu refocused his disgust into anger. He jumped back to the main elevator cable and clambered down to the lowest floor.

The doors were open. The metal remained bent from when Inosuke had forced his way into the chamber. As Zenitsu looked in, it felt wrong to call it a room. In his own Japan, he'd never seen a building as large as this cavern.

A full lake surrounded the iridescent white floor. The giant cross, with the mass of Lilith hanging therefrom, stood gargantuan. The LCL stench surrounded from all sides. He thought he could feel the fumes pressing down on him, trying to coax each muscle into giving up. The air felt as hot and sticky as a sauna. He guessed that the others in the room had no such issue.

In the centre of the white island of the floor, Gendo Ikari faced Nephilim, who stood only a few feet away. Zenitsu shuddered upon seeing the strange product of his and Rei's genes. Nephilim was as tall as Rei, but with more defined muscles. As Nephilim turned, they greeted Zenitsu with a wide smile and big eyes. Only a small voice of reason spoke amidst the guttural disgust he felt.

We can't judge Nephilim yet, the voice said. Rei had been created by Gendo, modeled after someone else. She deserved to live. She was human. Nephilim was created the same way. They deserved a chance.

So, Zenitsu focused on the man behind Nephilim. Gendo Ikari stood with a smug half-grin. A pistol hung from his left hand.

"Ah!" Nephilim said, "Father, you made it! I was worried I wouldn't be able to see you."

"Please don't call me father."

Nephilim took a few steps forward. "Oh, father, you're filthy. What happened to you?"

Zenitsu stared.

His muscles didn't move.

It was as if he'd failed for a moment.

Suddenly, he returned, uncaring for his surroundings. "I don't want to hear that from the maniac that sent a bunch of clones to try to kill everyone in this place! My eyes sting and my muscles hurt and I want to pass out. Why'd you send out all those puppets, anyway? Don't insult Rei like that!"

"Insult her?" Nephilim recoiled, putting a hand over their chest with a look of hurt. "This is the proper vengeance, don't you think? The people here killed mother. It is only right that they fall under her image."

Zenitsu marched forward. The logic made a twisted sort of sense, but it lacked maturity. It made sense, since they'd only taken their first steps a few minutes ago. "You don't know anything."

"Father—"

Zenitsu unsheathed his sword. Nephilim froze. Gendo remained unmoved. The thunder warrior spoke. "Gendo lied to you, Nephilim. He's the one that killed Rei. That scientist you murdered, sure, she played a part, too. Everyone else, here? They just wanted to fight the Angels. Most of the people in Nerv are innocent. Your mom, in case you forgot, lived to fight the Angels. I'm doing that, too."

Angel, Zenitsu repeated mentally. Nephilim is an Angel. If need be, there's no reason to hesitate an attack. Why, then, did he feel like it'd be wrong to murder them outright?

Slowly, Nephilim began to nod. "I think I see. You don't know why mom was born. Grandpa made her so she could start Instrumentality."

Zenitsu's vision began to distort. His lungs felt as if they were burning. "You each have three sentences to explain, or I kill Gendo."

Nephilim yelped in shock. Gendo's smirk lifted higher.

Nephilim reached out pleadingly. "You're not a murderer, father!"

"Stop calling me father! You have two sentences left. Two sentences. No more half answers! No more questions! Tell. Me. Everything. Now!"

Nephilim stepped back. Suddenly, the mystique disappeared. The green-haired mystery child was just that, a child. Sure, they were a mix of every human-like creature short of a demon, but they were a child nonetheless. A kid, easily impressionable, wielded power. A conniving adult turned that power into a tool. In the moment, Gendo reminded him of Muzan.

As Nephilim hesitated, Gendo spoke flatly: "Instrumentality will bring all humans together into a unified consciousness. The world as we know it will be reformed into an ocean of LCL fluid. Our bodies will disappear as we share a single mind without separation of thought or emotion."

Zenitsu nearly sheathed his katana. "You're kidding."

Gendo said nothing. Nephilim opened their mouth, but shut it and shook their head, as if suddenly recalling they only had two more sentences.

"That's your plan?" Zenitsu's shoulders drooped. "Your whole idea, the reason you've done all of this shit, is so you could murder everyone and turn them into a literal ocean of blood?"

Nephilim nodded.

Zenitsu smacked his face. "That's the dumbest shit I've ever heard."

Nephilim stepped forward again. Like the child they were, they held out two fingers. "There will be no more death or sickness when everyone enters Instrumentality." One finger lowered. "In this world, being alive is a source of pain, and people don't open up naturally to each other… unless there's something like Instrumentality to break down walls that… keep people from… knowing each other."

Zenitsu made no comment on the sloppily long sentence. The explanation made his head hurt almost as much as the LCL. This goal, this pathetic lack of understanding what it meant to be human, renewed his energy. In under a minute, Gendo had expressed everything Zenitsu hated about this world.

"Gendo, I hate you. You think making everyone one person will make things better? You think life will stop being hard? That struggle's part of being alive, idiot! People bouncing off each other: yelling and crying and fighting and loving and hating is called being alive! The shame, the anger, the fear, the hate. You work through that! You think people will work through anything if you turn them into blood soup?"

He imagined what it might have been like if Tanjiro or Nezuko or any of the Corps had known his mind when he first met them. They'd known him as a coward, but if they could have seen everything inside his mind: the pettiness, the entitlement. If there had been no barrier between them and all of that, they may never have allowed him to try. Worse, if he'd seen their minds, with all the hidden motives and pains and sufferings that they hid behind discipline and kindness, he would have latched onto those.

See! He would have glowered in petty self-righteousness. Look, you're not perfect!

No room remained for growth. That separation left the chance of pain. "Nobody knows what they're doing, asshole!" he yelled. "But most of us are trying pretty damn hard to get a little bit better! Don't insult everyone by trying to make it so nobody can improve! I don't want to be stuck in a soupy nightmare with you!"

Nephilim laughed awkwardly. "I think you're getting hung up on the soup thing."

Gendo shook his head. The smirk vanished. "Your opinion doesn't matter, Zenitsu. You cannot achieve Instrumentality."

"What?" Zenitsu asked.

"LCL is Lilith's blood," Nephilim pointed to the pale colossus. "You and the Slayers can't mix with LCL. So, you won't be affected if everyone turned into it."

Zenitsu shook his head and returned to his stance. "I'm done. Gendo, you're dying."

Gendo muttered something under his breath. Nephilim nodded. "Father, I have a gift for you. I hope it works." They stretched out their hands. The orange squares of an AT Field appeared in front of them.

Oh right, Zenitsu thought. Nephilim is an Angel. Still, he didn't want to kill them. He'd give Nephilim the chance he didn't give Rei.

He wanted to be sure to kill Gendo. With Nephilim's height, it seemed easy to pass the blade over them and kill the commander. But with an AT Field, things became a little more difficult.

Difficult, not impossible.

"Thunder breathing…"

Sparks flew around both Nephilim and Zenitsu. The AT Field pulsed quickly in front of Nephilim. Bright light pulsed out like a panicked heartbeat. Soon, they flashed at an impossibly fast rate. Nephilim began to shake.

"First form!"

Zenitsu rocket forward. His blade sliced over Nephilim in a perfect arc. The electrified steel struck the top of the AT Field.

Suddenly, there was a flash of light. The red room vanished. The heavy fog of LCL disappeared. Zenitsu stood on a dirt path between huts, his sword outstretched. It should have cut through Gendo's neck. But…

Cicadas buzzed. Birds flew away. He heard the sounds of nature. In the corner of his eye, he saw Nephilim lying dead on the ground.

"No… no…" Zenitsu begged in a whisper.

His dream and nightmare became reality. A soft voice screamed, "Zenitsu!"

The thunder warrior looked around. Many of his friends stood and gaped. A few dropped what they'd been carrying and rushed toward him. Nezuko charged forward, tears streaming. She practically tackled him in greeting. "I missed you so much!"

Kanao followed, with so many others in the Corps following. The scene was something he'd fantasized about. They focused on him with expressions of care. But he felt only horror.

Nezuko pulled back, Kanao asked, "What's that blood? Oh—" she covered her nose as Nezuko coughed. "What's that scent. Where are Tanjiro and Inosuke?"

Zenitsu barely heard them. He tried to make sense of it. Nephilim: a mix of Slayer, human, Eva, and Angel. An AT Field. Sparks. Nephilim got the AT Field spinning fast with the ability he got from Zenitsu. Slayer plus human plus Eva plus Angel. The Angels suddenly appeared without warning, the same way the Slayers had. Angels generated and maintained AT Fields.

Zenitsu broke the AT Field. They didn't break like shields; they tore like fabric. Nephilim had said this was a gift. Nephilim had called him father. Maybe…

His knees gave out. The sword fell from his grip. Kanao gave orders to prepare a bath and medicine.

"This was Gendo's plan…" he said.

"What?" Nezuko asked.

Zenitsu swallowed. Gendo had wanted Nephilim to generate an AT Field. He'd known, somehow, that Nephilim could generate an AT Field that could open a gate between worlds. The question remained if Nephilim had 'opened' that gate or if Zenitsu had broken through, but that didn't matter. In the end, Nephilim was another child used and sacrificed to Gendo's stupid plans.

Now, Inosuke and Tanjiro were still there. No, things were worse. A flood of LCL. Instrumentality. Gendo was every bit as bad as Muzan had been.

"I need to go back," Zenitsu said.

Nezuko grabbed his shoulders. "Calm down. Talk to us," she coughed and turned away. The LCL stench must have hit hard, especially when mixed with all the blood that clung to him.

Kanao asked from a few feet away. "What happened?"