The world didn't break with an explosion.
It splintered—quietly, invisibly.
Each moment, each second, something small would flicker. A Titan with three arms. A soldier's ODM gear igniting in blue flame. Wind that curved against logic.
The laws of the world were... being rewritten.
And Arata knew why.
Because this wasn't just his isekai story anymore.
Someone else was writing it now.
---
Scout HQ – Tactical Briefing Room
"Something's wrong with the Titan template," Hange said, slapping a sketch on the table.
The drawing showed Annie's new form. Spiked bones. Unnatural flexibility. Movement patterns that broke all military logic.
"She moved like... she was dancing," Hange muttered. "And these bone blades... they're not evolutionary traits."
"They weren't," Arata said quietly. "They were designed."
Everyone turned toward him.
"Designed by who?" Erwin asked.
Arata hesitated.
How do you explain to people who've never seen a TV screen that their world is now fictional clay?
---
Arata's Explanation – Filtering the Truth
"I… come from another world," Arata began slowly. "A place where your world exists as stories. Books. Drawings."
Eyes narrowed. No one laughed.
"I used to read about this place. You. Titans. The Walls. It was all fiction to me. Entertainment."
"So… you're from the outside," Mikasa said, half-accusation, half-realization.
Arata nodded. "But when I came here… something came with me. A fragment. A virus, maybe. Something from another story—a different one."
They didn't know what "chakra" meant.
They didn't know what the "Uchiha" were.
But they understood one thing:
Another power was infecting the world—and it wasn't from Ymir.
---
Anomaly Spreads – Beyond the Walls
Far outside Wall Rose, scouts observed a Titan sprinting through the forest. Faster than any before it. When it jumped—it vanished for a moment midair and reappeared meters away.
"Teleportation?" the scout captain gasped.
The Titan hit the ground and kept running. White marks shimmered across its body—symbols no one had ever seen. They pulsed like veins of light.
Back at headquarters, Arata examined the report and clenched his fists.
"…Kaen's giving them jutsu."
---
Levi's Journey – Into the Chapel
While the scouts scrambled, Levi walked the ruins of an old chapel—the one he used to visit as a child.
He wasn't alone.
From behind a vine-covered pillar stepped a man with his same eyes—older, calmer, colder.
Ren.
"Still carrying that soldier's weight?" Ren asked.
"I don't carry it," Levi answered. "I turn it into steel."
Ren grinned, lifting a hand—and from his palm, a spinning seal emerged. Not magic. Not Titan power. Something else.
"Kaen gave me this. He said it's power from a story that shouldn't exist. I didn't believe it—until I started seeing my own body change."
Levi's blade was drawn before Ren finished speaking.
---
Armin's Analysis – Patterns Without Names
Armin stood with Arata in the war room, looking at Titan battle footage.
"These new forms… they're not random mutations," he said. "They're intentional. Crafted. As if someone is adding rules to our biology."
Arata nodded. "That's exactly what Kaen is doing. He's trying to re-author the world."
"You said he's from another story?" Armin asked.
"Yes. A world where people control energy from inside their bodies. They can manipulate elements, enhance themselves, do impossible things."
Armin blinked. "And what's it called?"
Arata hesitated, then answered:
"…Naruto."
It meant nothing to them. But it meant everything to him.
---
Kaen's Offer – The Beast Titan's Choice
Zeke stood on the peak of a ruined tower. The wind howled through the bones of the city.
Kaen appeared beside him—not as a physical being, but as a thought, a vision stitched from Arata's old memories.
"You're brilliant, Zeke. Calculating. Merciless. But you are limited."
"By what?"
"By biology. By the bounds of this world's laws."
Kaen opened a scroll—an ancient parchment with pulsing red glyphs.
"Accept my rewrite," he said. "Become more than a Beast Titan. Become a Beast Sage. Command nature itself."
Zeke didn't answer. Not yet.
But he didn't walk away either.
---
Final Scene – Levi vs. Ren: Clash of Reality
Ren dashed forward, his body enhanced by invisible force.
Levi sidestepped and sliced—but his blade met a spiraling defense, like hardened wind.
"You're not a Titan. You're not Ackerman-strength alone. What are you?" Levi growled.
"I'm the first rewrite," Ren said. "And I'm not the last."
Their blades clashed again, steel against concept.
Arata stood on a rooftop above, watching.
And finally whispered to himself:
"I didn't bring just power into this world. I brought contamination."