Just a Cowardly Thief

Ace was startled when he heard the Sword's words and narrowed his eyes. He clearly didn't believe it. But for some reason, he didn't think it was lying. 

Just what could've made a Treasure Spirit so afraid? What was the forbidden boundary, and what was imprisoned there? 

The chains continued to break one after another as the golden mass of energy was becoming more and more rampant with its thwacking on the formation and symbols on the formation were slowly fading. 

"YOU FOOL, whoever you are! Quickly retrieve the keys before it's too late!" The sword's appalled voice rang again, "There is a monstrosity that can't be killed! It is sealed in the depths of the sea! Last time, too many lives were lost just to suppress it and then sealing it here far away from its followers where they can't even imagine its location.