"I understand, but I still have some questions."
Fujimaru Ritsuka raised one hand.
"Mr. Napoleon, you said that the foundation of a Lostbelt is the Fantasy Tree, and that cutting down the Fantasy Tree would erase the Lostbelt from the surface of the planet. Is that right?"
He met Napoleon's gaze, looking into his eyes.
His eyes seemed to tremble slightly.
"That's right."
Napoleon nodded.
He had—more or less—already guessed what Fujimaru Ritsuka wanted to ask.
"Then after it's erased, what will happen to the people in this Lostbelt?"
Lostbelts were different from Singularities.
A Singularity was altered history rooted in Proper Human History. As long as the anomaly that caused the alteration was removed, the Singularity would return to the correct history. Even if minor changes remained, they would not bring about any particularly serious consequences.
But Lostbelts were different.
Lostbelts were also incorrect histories, but they were incorrect histories that had continued all the way into the present.
Through the Root of Fantasy, such erroneous histories had been forcibly nailed onto the Earth that had been bleached white.
In other words—
"A Lostbelt is, in truth, already a [possibility of civilization]. Even if it is a mistaken possibility in our eyes, it is still a possibility that has endured through the ages and become fixed in this place."
Napoleon looked into Fujimaru Ritsuka's eyes and solemnly told him the truth.
"In other words, this place is a [world]."
"The Fantasy Tree is the foundation of that world, the foundation that makes this possibility real."
"To cut down the Fantasy Tree and erase the Lostbelt is, in truth—"
"...To destroy the world."
Fujimaru Ritsuka's hand dropped.
More precisely—
It [fell] down.
It struck the edge of the bed.
"How... could this be?"
Mash's eyes widened. If one looked closely,