"The world is like a tree."
"External thieves are like pests."
"When pests reside on the tree, they can be caught and removed by hand; when pests cling to the bark, birds peck and eat them; though the tree may become unsightly with pits and hollows, its core remains unharmed; but if pests bore into the heart of the tree, it becomes riddled with holes, rotten wood beyond carving."
In the tower of Black Prison Castle, Professor Yao stood at the edge of the wall, looking up at the pitch-black sky overhead, and spoke softly: "Now, the great tree of the Black Prison World has already been infiltrated between the bark."
Thunder rolled from afar, and in an instant, turned into bolts of lightning blasting overhead of Black Prison Castle. The booming sound drowned out the howls of rioting prisoners outside, and even overpowered the explosive sounds of various spells.
"Hoo!"
