Shadow World

s were a kind of parallel worlds and the most dangerous phenomenon mankind has ever seen that occur each year. Like an infinitely long corridor with countless rooms on each side; there are countless worlds, each with their own bizarre set of rules.

Without a doubt, however, the most dangerous characteristic of a is its potential for an ‘Encroachment’ event to occur. Encroached land is smothered in a thick, black fog, and it becomes impossible to know what’s happening inside. Only one thing is certain: no living being has ever entered encroached land and returned alive. It is simply a place where life cannot exist.

Origin of the s
s are created by the Artemis System recreates the past and turns it into the correct history for the prosperity of all intelligent life. However, the system became the very thing that threathened the world.

Clearing the s
‘Clearing’ the prevents it from encroaching upon our reality. If the event of a given is based off of a past war in our world—the ‘background’—and the victory of that war consisted in demoralizing the enemy, then the ‘clearing’ would involve defeating the enemy in the exact same manner—this would be the ’s ‘objective.’ Every  has its own background and objective, and completing that objective ‘clears’ the.

Organization
The goal, then, is to clear all the s that appear. And the two rival organizations, Western Kingdoms and Hebrion Academy, stand at the forefront of this movement.

s didn’t disappear until they were cleared. As time went on, the existing s would continue to pollute and encroach on their territory. With the thousands of s available, they were split between Hebrion Academy and the Western Kingdoms. The most difficult instances were given to Hebrion Academy graduate students, whilst the actively enrolled students would often find themselves in low class Shadow Worlds to build experience.

Knighthood
According to the rules of Hebrion Empire, any group that can successfully clear a Class 3 Shadow World will recognised for their strength and organisational power, and will be given the same power as Knights.

Any party that established such a merit at Hebrion Academy will be able to act without going through the Academy, which meant that it had the right to act alone.

Accessing the s
A long time ago, s could only be accessed via Teleportation Gate exactly where the spawned. With the technological advancements over the past 30 years, expeditionary members are now able to enter the Shadow World from anywhere using Fifth Circle Space Manipulation magic. In order to participate, all an expeditionary member have to do is select his preferred and enter the gate.

Death
If someone were to meet their end in a, their corpse would become a part of the world. Once the was cleared, it would disappear along with the world.

Classes of the s
The s are divided into 10 levels, and depending on the ranking, the number of deaths in a can be estimated.