The colossal Battle Arena was conspicuously out of place amidst the architecture of the Mortal World. Mu Can knew of the arena's existence from descriptions within an ancient tome, where it was said to be a place of amusement for nobles. At that time, Mu Can had no clear understanding of what "nobles" meant and had even made a point to inquire further.
It turned out that the term referred to families with ancestors of extraordinary strength at their helm, whose power was passed down from generation to generation, sustaining and glorifying their lineage. Such families were recognized as nobles, and it was quite apparent that those Hidden Families within the Mortal World were indeed the most elite among them.
After all, not every family could boast of finding other spaces within the Mortal World suitable for human habitation.