This will mostly stick to canon and fit in-between DR2 and DR3: Future. The main divergence is that Junko doesn't brainwash them with a video, and instead actually uses her talent to convert them into her despair religion. Everyone also won't wake up instantly, and will do so one-by-one over a series of months. Oh and Kazuichi will stop idolizing Sonia and learn to understand her as a person.
WARNING: There are violent scenes, mainly in flashbacks to their time as remnants of despair. I'm not an amazing enough writer to make them too graphic, and they won't be the main focus, but please turn away now if you're easily disturbed by that kind of content.
Shrieks of pain and loud sharp cracks filled the air, accompanied by the pungent metallic smells of blood and gunpowder. Walls of concrete etched with a deep crimson red graffiti surrounded rivers of thick red liquid, hiding cries and wails in their creases. Each series of rattling cracks lead to the sudden silence of the cries, and the cruel sounds of flesh squishing and splattering. Sickening smells of rot and death soon followed, and sometimes faint moans and howls of loss and grief could be heard among the chaos - succeeded yet again by another repeat of the barbaric cycle.
Upon first sight, one might assume that this was a battleground of cold-blooded malevolence and cruelty, born from the ignorance of a war of ideals. They would be correct in their assumption, and yet also horribly wrong. For this was not a battleground of anger, nor one of hatred, nor one of vengeance. No, the ones who caused this scene did not cling to noble ideals, or desire an outcome that would satisfy their greed, lust, pride, envy, wrath, sloth, or gluttony. They made no declarations or demands, and only desired one thing from the ones they declared war against.
It was a deluge of despair-inducing despair. For despair, by despair, from despair. A despair to squash all hope, and invade the hearts of all it set its sights upon. And in the centre of this despairful scene stood a figure with punk hair, a jumper that went down to the ankles, and an enormous machine gun-like contraption. They were followed by a trail of a deep, deep red, which lead to their own gruesome blood-covered body. They began to wail.
It tore at his heart to see the hundreds of innocent corpses that lay before him, none of which deserved such a heartless and cruel fate. It was an act of pure evil – and worst of all, he was the perpetrator. Kazuichi Soda, a genius mechanic that only wished to help others with his creations was instead using them to slaughter innocents by the thousands. His heart was filled with such powerful despair, despair greater than he had ever felt before - and he could no longer contain it. With the entirety of his very being, he let out a great shout.
"This despair is goddamn freaking awesome!"
Kazuichi let out a high-pitched shriek, and thrusted his arms into the air. However, all that came out was a string of bubbles, and his hands gently touched the solid surface above. They were no match for the resistance of the blood that he was drowning in. He was going to die, soaked in the blood of his victims. He was terrified. Or was that really the case? After fully regaining consciousness, he realised that it wasn't blood and concrete, but just clear liquid and glass. With a sudden click, the liquid drained away, and the glass opened. His vulnerable body shivered as the sensation of waves of air engulfing him - it had been a while since he last experienced this. And then it all came back to him.
"That's right… the killing school trip. We were trapped in that stupid program, because of Monomi… but we beat Monokuma and escaped, and-"
Suddenly Kazuichi reached a realization, "wait a second, Miss Sonia! And everyone else! Did they escape too?!"
He attempted to leap out of his pod, but his muscles were not up to the task, frantically wriggling like snakes at the slightest bit of pressure.
"Crap, when did I last use these things? Why won't they work now of all times!"
Frustrated, Kazuichi resorted to pushing his back against the side of the pod, allowing him to stick his head slightly over. Beyond the confines of his pod lay countless others, emitting a discomforting glare of neon green light. The room itself was surrounded by a sea of dim red and blue lights, making it difficult to see anything beyond the strange silhouettes of futuristic contraptions crowding the room. He made a mental note to investigate and dismantle them at a better time.
"Hey, anyone there? Um, Makoto wasn't it, ya listin'? Stop playing games and help a guy out here, please!", Kazuichi cried out, starting to panic. Did those guys from the Future Foundation abandon them? Was anyone else going to wake up? Would he be stuck here forever, trapped until he starved to death? Kazuichi began to sob, crouching back down and burying himself deep into a ball.
After almost completely hiding his head in his knees, he quickly shot back up. It was faint, but he could hear the shuffling of footsteps in the distance. They seemed to be coming from the other side of the wall; it was probably a door. Immediately confirming his conclusion, it slowly began to creak open. From the void of darkness, a shadowy silhouette emerged, barely illuminated by the weak lighting. It started to approach the frozen Kazuichi. As it came closer, he was able to distinguish some features: dark pants, some kind of brightly coloured shirt, and maybe a tie? Based on the smooth long dark hair, he quickly concluded that it was a girl. Probably that Kyoko girl, looks like he'd struck lucky by getting the cute smart one.
Or not. After getting an even closer view of the figure, there were two features that made Kazuichi recoil back in shock. Firstly, the hair wasn't just long – it was absurdly long, almost touching the floor. It was also unnaturally stuck into place, barely avoiding tripping the figure up at each step. But the truly terrifying part was the eyes. The right eye was a mesmerizing bright green, and the left eye was a glowing bright red. Etched into both was an odd target radar pattern, seemingly piercing right into him. It was something not human, and it completely froze him in place – not that he was capable of escaping anyway.
"D-Don't c-c-come a-any c-c-c-closer…", Kazuichi fearfully stuttered, barely able to make a sound. But the figure wouldn't listen – it kept walking forward without any hesitation. He knew he was done for.
"I wish I could've seen Miss Sonia one last time", he thought regretfully. "Maybe I'll find another beautiful blonde princess in my next life". Inspired by his fantasy, he managed to work up a slight amount of courage, and fearlessly faced his attacker - or at least he pretended to.
"I-I'm not scared, M-Miss Sonia and I are destined to reincarnate for all eternity, s-so it doesn't matter if I d-die. Y-You'll never b-break our unbreakable bond!"
The figure paused and frowned.
"What the hell are you going on about Kazuichi?"
To his surprise, it was a familiar voice. It didn't fit the imposing figure in front of Kazuichi, and didn't sound malicious. A lightbulb sparked in his head.
"H-H-Hajimeeeeeee?!"
"Yeah, it's me. What were you expecting, a ghost?"
"Freaking hell man, why didn't you say anything earlier? I thought my engine was about to die out!" He took a closer look. "And since when did you grow Rapunzel hair? Did your pod mess up, or are you into that kind of thing?"
The not-actually-all-that-dangerous Hajime responded with a sigh. "It's… a long story, but basically the experiments gave me rapid hair growth, and I never bothered cutting it. Don't ask why."
"Experiments?! You mean we were exp- ", Kazuichi almost exclaimed, before more memories flooded back into him. "Ohhhhh right, you're also that Izuru Kamukura guy that the messed-up bitch wouldn't shut up about. That makes sense then…" he said before suddenly recoiling back again. "Wait a second doesn't that mean you're- ".
"Um, I can guess what you're about to say, but no, not really", Hajime interrupted. "I've only been awake for a few hours, and I don't really remember much, other than what happened in the simulation."
"Nononono, it's still crazy dangerous! You could remember everything at any moment, and kill us all! I bet that left eye of yours can shoot lasers, you Ultimate Superman!"
"Erm, I think you're taking this all-talents thing too far here. And besides, you could say the same about yourself, right? We all have a ton of memories we're better off forgetting."
Images from Kazuichi's nightmare flashed back into his head. The deep red blood, the smell of rot, the wails and cries; he almost gagged at the thought. "Y-Yeah, I guess you're right…", he said, dazed.
Hajime immediately noticed Kazuichi's change in demeanour, and thought it would be best to change the topic. It wouldn't help to force memories out, lest they arrived at the worst-case scenario. He didn't want to think about that. "Anyway, you're the first to wake up, other than me. It looks like Sonia, Fuyuhiko and Akane won't take too long to wake up either, according to Kirigiri. As for the others, well, it's more uncertain, but the possibility still exists. At least we can hope so."
"Then we're going to make that possibility a reality. Because that's the future we're going to create, right?"
Hajime smiled. He might still be his cowardly and drama queen-like self, but the pink-haired mechanic had grown since Hajime first met him. "Yeah, that's exactly what we're going to do." Maybe he was even on track to moving on from his obsession with-
"But seriously, who cares about them! We need to check on Miss Sonia right now. When she gets a kiss from her destined love, she'll awaken in an instant! I can already hear her whispering: 'Kazuichi Soda… my hero… p-please save me from this eternal sleep'. Oh, Miss Sonia, I'm coming to save you!"
Hajime sighed. "I guess old habits die hard, huh…"