It was raining in Soul Society.
A young man with moss-green hair hurried through the misty backstreets outside Seireitei, coughing intermittently beneath his umbrella. His name was Yushima Osu, an ordinary researcher of the 12th Division, no seat, no rank, no authority.
Just another cog in the wheel.
"Osu! You're back!"
An old neighbor lady waved at him as he passed. He nodded absently and quickened his pace.
This was the district where he'd grown up. When he got accepted into Shin'ō Academy, everyone here had been so proud. He was once a bright, hopeful young soul—eager to become a Shinigami.
But that dream? Dead before it even began.
Sure, the instructors at Shin'ō praised his Kido talent as "unparalleled." But his body—frail, anemic—couldn't support anything beyond basic spellwork. Forget Zanjutsu. Forget Shunpo. He couldn't even meditate for long enough to speak with his Zanpakutō.
And with a body that couldn't endure spiritual strain, even communication with his sword was torture.
So, after graduation, rejection after rejection followed. Even regular humans could probably beat him in a fight.
Eventually, Muguruma Kensei, then-Captain of Squad 9, transferred him into the 12th Division—more for Osu's safety than anything else.
There, Osu had finally found some worth, helping Urahara Kisuke develop the Gigai.
Only for the tech to be instantly outlawed by Central 46.
Osu had hoped to secretly continue researching Gigai tech on his own. Maybe he could fix his body somehow.
But then Urahara defected. Everything he'd worked on became classified, locked away. Only Kurotsuchi Mayuri had clearance now.
Osu's last flicker of hope was crushed.
"Am I the unluckiest Shinigami alive…?"
Back in his dark, candleless room, Osu slumped to his usual corner, ready to curl up and survive another day in shadow.
But tonight—something was different.
His foot struck something soft.
"What the—?"
He froze. Panic prickled down his spine. He lit the dusty candle on his desk. Its faint light fell across the floor…
…illuminating a man.
A Shinigami. Barely breathing. Pale. Collapsed.
"Who are you?! What are you doing in my house?!"
Osu stayed sharp. Just because the guy looked half-dead didn't mean he was safe. Plenty of monsters looked weak right before they killed you.
"You don't recognize me?"
The man's lips trembled, voice faint as mist.
Osu squinted. Something familiar—
Wait.
No way.
This was him. The man labeled a traitor. Once Vice-Captain of Squad 11. The one who fought five captain-class Shinigami at once… and escaped alive.
Higashi Shuuichi.
Osu stumbled back, hands shaking.
Oh no.
He was the unluckiest Shinigami alive.
Meanwhile, from his crumpled position, Shuuichi rolled his eyes.
Seriously? I've become that infamous?
This guy—this Osu—should've been a future genius. And here he was, plastered to the wall in fear.
All that effort—Shuuichi had deliberately used his Zanpakutō's ability to drain most of his spiritual particles just before Osu arrived, making himself look frail.
And it worked… too well.
"Y-You… You're Higashi Shuuichi…"
"You don't need to be afraid," Shuuichi rasped, lying through his teeth. "I'm gravely injured. Might not recover for a long time."
Of course, anyone who knew him would call BS instantly.
Infinite regeneration and all.
But Osu didn't know.
So he believed it.
"…Really?"
Seeing Shuuichi's haggard look, Osu's mind began to race.
This man—who once soloed five captains—was in his room, weak, vulnerable. If Osu could get even a scrap of guidance from him…
This could be it. His turning point.
Forget Soul Society's laws. Forget the traitor label. Osu had once risked everything to keep researching Gigai even after it was banned. What was harboring a wounded Shinigami compared to that?
This was his shot.
"You think I need to lie to you?" Shuuichi murmured, tracking the shift in Osu's expression.
Got him.
"Just need a place to rest."
"…You can stay," Osu replied. "But I have one condition."
He tried to keep his voice firm, but to Shuuichi—trained eye and all—he might as well have been a child pretending to be brave.
Shuuichi played along.
"You know who I am, and you dare make demands?"
He released a flicker of spiritual pressure.
Enough to make Osu sweat bullets.
He'd already cloaked the room with reiatsu-dampening tech. No one would notice.
Osu trembled but held his ground.
"I-I know what you're planning. But I'm Mayuri-sama's deputy. If you kill me, you won't get away with it."
Lie. A complete bluff.
In truth, Osu was on the bottom rung—barely tolerated by Mayuri, who loathed anyone associated with Urahara. If anything, his position was worse now than under Kisuke.
Shuuichi, of course, knew that.
But he widened his eyes in mock surprise.
"You… you're his deputy?"
Osu visibly relaxed.
Hook, line, sinker.
"I'm not asking for much," Osu said, pushing forward. "I want you to help me. I'm done living like this. I want to be stronger. Strong enough to make those who mocked me kneel!"
He added a respectful, "Vice-Captain Higashi," for good measure.
And Shuuichi couldn't help but smile inwardly.
This was perfect.
Osu's core problem? His body couldn't withstand his reiatsu. Solution? Train him against lower-strength constructs, ramp up gradually, build durability.
Easy.
But more importantly—this was a stepping stone.
Osu wasn't just any weak researcher. In the original timeline, he would one day develop modified soul technology—the foundation for soul reconfiguration experiments later perfected by Inaba Kagerōza, his splintered personality.
When it came to soul science, Shuuichi trusted Osu's potential even more than Mayuri's.
Because Mayuri was a wild card. Genius, sure. But one Shuuichi wouldn't bet his life on. The man was the kind to install secret kill switches just for fun.
Osu?
Desperate. Hungry. Talented.
And now loyal.
And so, in a room no one cared about, lit by a single candle, a strange pact was formed between a "traitor" and a "nobody."
Both walked away thinking they'd struck gold.
A devil's contract?
No.
This was Grandpa Cheat Code meets Fake Protagonist.
And the story had only just begun.