"Worlds were like Trees."
"External enemies were like borers."
"Bugs perched on a Tree could be caught and removed with an outstretched hand; bugs clinging between the bark could be pecked apart and eaten by birds. Though that would inevitably leave pits and scars, it would not harm the wood itself. But if bugs bored into the heartwood, then the Tree would already be riddled with holes—rotten wood could not be carved."
At the main tower of Black Prison Castle, Professor Yao stood at the edge of the battlements, head tilted up as he gazed at the pitch-black sky overhead. He said softly, "Now, the great Tree that is the Black Prison World has already had bugs burrow between its bark."
Rolling thunder drew near from afar, swiftly transforming into bolts of lightning that exploded above Black Prison Castle. The crashing booms not only drowned out the howls of the rioting prisoners outside the castle, but even suppressed the sounds of countless spells detonating.
Whoosh!
A ball of Green Flame suddenly erupted from an open space not far from Professor Yao. As the flames danced, a male wizard in a black robe appeared, kneeling on one knee.
"Report!"
"The Divination Group has sent an urgent message. The Demon Allied Army has breached the Black Prison World's fetal membrane, corroding several passages through the crystal wall surrounding the realm. The demons from Outside the Realm may descend through those passages at any moment. The Divination Group recommends—"
"I know, I know."
Professor Yao waved a hand, interrupting the wizard's report. Lowering his eyelids, he glanced at the magical barrier flowing with seven-colored radiance over the inner castle and replied quietly, "Everything is proceeding according to plan, isn't it?"
Whoosh!
The ball of Green Flame appeared again, burning from the wizard's feet