The afternoon sun in Sugisawa Municipal High School was a thick, sickly gold, filtering through grime-streaked windows. It was the kind of heat that turned a classroom into a sensory deprivation chamber. For most students, the drone of the history teacher was just background noise to their scrolling on phones or half-hearted note-taking.
For Jin Kurosu, slumped in the back row, it was the moment the world stopped making sense—and then started making too much of it.
Inside his skull, the "quiet" was being shattered. It didn't happen with a gentle whisper. It happened like a hard drive being force-fed the library of Alexandria in a single second. Memory fragments—not his own, yet intimately familiar—tore through his consciousness. He saw a man in a straw hat laughing against a blue sea; a ninja standing atop a stone monument; a boy with green hair shattering his own bones to save a friend.
Then came the voice. It wasn't human—it was too clean, too structured. It sounded like the hum of a supercomputer translated into thought.
> [INITIALIZING SOVEREIGN ORIGIN CALCULUS...]
> [DATA CORRELATION: COMPLETE.]
> [EGO SYNCHRONIZATION: 100%]
> Greetings, User. I am Aletheia.
> Current Status: Latent Cursed Energy Awakening.
> World Designation: [Jujutsu Kaisen].
>
Jin's eyes snapped open. He didn't lift his head immediately, instead staring at the wood grain of his desk. The "toll" he expected from such a violent mental transition never came. There was no headache, no nausea. His mind felt terrifyingly sharp, as if someone had replaced a flickering candle with a high-intensity laser.
He looked to his left. A few seats away sat Itadori Yuji, looking bored. The protagonist. The vessel.
"Aletheia," Jin thought, the name feeling like a cold razor in his mind. "Report."
> [STATUS REPORT]
> User: Jin Kurosu
> Sovereign Authority: 0.01 (Rank: Civilian)
> Limitless Engine: Active.
> Note: Your physical vessel is currently 'Standard Human'. To survive the coming 'Cursed Era', immediate refinement is required. Accessing 'Akashic Library' (Naruto, One Piece, Bleach, MHA) for optimization.
>
"Don't interfere yet," Jin commanded internally. "We let the plot move. We wait for Yuji to meet his grandfather. Once he leaves the school, we start the synthesis."
The After-School Refinement
The school day ended with agonizing slowness. Jin stayed in the shadows of the hallway, watching as Yuji sprinted off toward the hospital. The air in the school was already beginning to change. As the sun dipped below the horizon, the "grease" of cursed energy began to leak from the walls—a foul, rotting smell that only Jin could perceive.
He walked into the empty West Building, his footsteps echoing in the silent corridor.
"Aletheia, I need a baseline. I have the knowledge of those worlds, but I need the power to back it up. Start the synthesis. Use the 'Big Four' logic. No tolls."
> [SYNTHESIS INITIALIZED]
> Current Module: [The Core Engine].
> Logic 1: [Naruto - Chakra Control] -> Translating to Cursed Energy Efficiency.
> Logic 2: [One Piece - Busoshoku Haki] -> Translating to Physical Reinforcement.
> Refining... Success.
> Sovereign Authority: 0.20 (Equivalent: 2 Sukuna Fingers).
>
Jin felt it. A sudden, massive surge of power that should have torn his veins apart, but didn't. His body remained calm, his pulse steady. He raised his hand. It didn't flicker with the messy, blue flames of a standard sorcerer. Instead, his energy was invisible, compressed so tightly it distorted the air around his skin.
He focused on the wall in front of him.
"Shunpo," he whispered.
In a literal flicker, he was on the other side of the room. No friction, no muscle strain. He turned and struck a locker with a fist coated in the invisible "will" of Armament Haki. The metal didn't just dent; it folded inward like paper, the force of the strike entirely contained within the point of impact.
> [NOTIFICATION]
> Condition Met: Initial Power Threshold Reached.
> Current Capacity: You are a 'Hard Counter' to most Grade 1 Curses.
> Warning: Aletheia detects a Special Grade cursed object being tampered with in the West Wing. Fushiguro Megumi has entered the premises.
>
Jin stood tall, his silhouette dark against the moonlight. He felt the massive, jagged pressure of Sukuna's finger beginning to bleed through the school's atmosphere.
"The King is waking up," Jin murmured. He didn't look afraid. He looked like a man who had finally found a math problem worth solving. "Let's see if he can handle a variable he didn't account for."