When the Demon King’s Son Is Reborn as Gojo’s Younger Brother

After Zero, a descendant of the “Demon King” and “Upper Moon Zero,” was killed by a Hashira of the Demon Slayer Corps, he was reborn as Gojo Zero.

Gojo Zero has a strongest older brother who shares neither parent with him and spends all day bullying him for fun.

He also has a System that tells him this is a manga called Jujutsu Kaisen, and that his brother is a breakout fan-favorite character in it!

Gojo Zero suddenly understood. No wonder people were always declaring they wanted to be his brother's wife, secretly trying to take him away, or mourning him long before he died.

Turns out they were all people who had transmigrated!

And then the System told him: in the future, Gojo Zero will become a world-destroying BOSS!

Gojo Zero: Me? A big boss? Seriously?

The System advised him to start clearing his name now, so he wouldn't get assassinated by transmigrators every day.

Gojo Zero smiled. “I'm bored, so I can play along with the transmigrators. But if they provoke me, I'll wipe them all out.”

*

The transmigrators took advantage of the fact that the future BOSS, Gojo Zero, was still “weak.” They all wanted to get rid of him as soon as possible, whether by attacking him directly, using someone else to do it, or scheming to turn the brothers against each other. Their tricks kept coming.

But he cut them down like melons and vegetables. They couldn't fight back at all.

The transmigrators: The intel was wrong!

Didn't it say Gojo Zero was a pitiful little thing at the start? This is clearly a Demon King!

The young boy's face was splattered with blood, his expression as cold as ice. “Don't come near Gojo Satoru again. He's mine.”

When Gojo Satoru beckoned, Gojo Zero scampered right over.

Then Gojo Satoru turned to the transmigrators and said with a sunny smile, “Actually, I don't want Zero to make friends at all. If I wake up in a bad mood one day, you might find yourself in pieces when you open your eyes.”

At last the transmigrators understood: damn it, these two were a pair of crazies, each just as devoted to the other!

The manga they'd read was a trashy fan comic drawn by a fan creator driven to take revenge on the world by the original author!

Fan creator: Now that Gojo Satoru is dead, I'll make the whole world die with him!

But the transmigrators realized the truth too late. They could only return to their own world after they died.

Gojo Zero: In the end, this world has gone crazy in ways I can't understand.

But at last he found the mastermind who'd been causing trouble all along, hiding like a cockroach: Brain-kun.

*

Brain-kun had always lived a leisurely life, causing trouble with Sukuna's fingers and making a vessel for Sukuna...

Then one day, the youngest son of the Gojo family found him.

As soon as they met, he said flippantly, “So you're pregnant. Guess I can't kill you. Then come work as the manager at my factory.”

Then Brain-kun witnessed a terrifying sight: every employee in the factory was a cursed spirit!

And they were all forced to work nonstop, twenty-four-seven.

Brain-kun: Damn capitalist!

But for the sake of Sukuna's vessel, it couldn't leave this body at all!

The day production was complete, Brain-kun couldn't wait to move elsewhere, but was instantly teleported back inside the factory.

Before him stood a white-haired young boy, fangs showing and an innocent expression on his face. “We signed a thousand-year contract. How could you break it?”

When Brain-kun heard that Gojo Zero had suddenly disappeared, he wanted to celebrate with the whole world.

As expected, the wicked live long. He was the one who'd lived the longest!

*

Shibuya Incident.

The Special Grade cursed spirits surrounded Gojo Satoru, while Brain-kun's Prison Realm began to stir.

Brain-kun: With Gojo Zero out of the way, nothing can go wrong this time!

Gojo Zero suddenly appeared. “If you're going to seal away someone else's older brother, shouldn't you at least ask his little brother first?”

Brain-kun: What the hell, why are you here again?

Gojo Zero: “A certain god said my presence was throwing the balance between both sides off, so he took me to train with him. He said he'd only let me out once my training was complete.”

Who knew I'd get banned and have to train for ten years?

Brain-kun timidly asked, “The god was called...?”

But when it was cut into thousands of pieces, it understood.

The god was named Tsugikuni Yoriichi.

And yet it still wasn't over.

The strongest clutched Gojo Zero's wrist. He was covered in blood and radiated a chillingly murderous aura, the very picture of a madman, but he was still smiling.

“If you're going to leave, shouldn't you at least ask your older brother first?”

At last, the crematorium was burning right under his feet.

*

Bonus scene:

The strongest finally learned that his little brother was a demon who'd transmigrated from the Taisho era.

The strongest: Then let me meet your in-laws (crossed out), I mean, your family.

Zero said firmly: I don't have a family.

The strongest: Then who is this person who looks so much like Michael Jackson?

Zero: He's the world's most despicable man, who somehow survived being cut into thousands of pieces.

Muzan gritted his teeth, but under the strongest's intimidating gaze, he could only put on a show. “My son is rebellious and has broken my heart.”

Then... Holy crap, Yoriichi!

Why is Yoriichi still around in this era?

1. This should count as a goofy power fantasy. It crosses over with some obscure anime, Japanese films, and horror manga.

2. The CP is obvious! Both are powerful, and Gojo Satoru deserves the best possible ending.

3. Zero never ate shit, and he genuinely can't stand Muzan.

Theme: Finish what you start, and good people get what they deserve.