Chaos Zone

Chaos Zone (混沌領域) or Chaos Environment (混沌環境) is an otherworldly dimension where the Chaos Beasts emerged in Mass for the Dead.

Background
The result from a crack in reality in "this world," leading to the Chaos Zone which suddenly comes and goes.

Needless to say, it is not clear what is waiting. Different enemies existences are assumed like Shadow s. Their behavior is unexpected, and the situation is left to the discretion.

Momonga who is interested in this strange phenomenon sends a team to survey this mysterious space and bring back as much useful information and resources as possible for himself and the Great Tomb of Nazarick.

In a Chaos Zone, strange shadows lurk in the background and appear vaguely humanoid. Beside Chaos Beasts, there are Contaminated Beasts which are hunted by the former as well as many unconscious or dead victims that were brought from the New World. Oddly enough these victims are ignored by the Chaos Beasts and are unmolested as the Chaos Beasts are only attracted to prey that move within the domains of the dimension.

Though according to Gazef Stronoff's observations, he witnessed bodies that seem partially eaten or even swallowed whole by something in the mysterious relam.

Mass for the Dead Arc
During a colossal attack on the city of E-Rantel, the protagonist was among those who were taken to the Chaos Zone either through a rogue Crack or the invisible enemy. The protagonist finding himself in a strange world, sought to escape and return to the original world. Though powerless in a world filled with aggressive monsters, he was found by Gazef Stronoff who protected him, until he reached a nearby Crack.

After crossing the threshold, he found himself in a forest a little ways form Nazarick. Upon returning to Momonga, he learned that he along with Yuri Alpha, CZ2128 Delta, Solution Epsilon, and Slimeko were missing for several months. Since the Sorcerer Kingdom now had a viable way to retrieve their remaining comrades, a rescue operation was prepared using new equipment.

Due to time being much slower on the "other side", the protagonist led another party a month later, composed of himself, Narberal Gamma, Lupusregina Beta, and Entoma Vasilissa Zeta and several Shadow Demon s into the Crack.

There without wasting any time, the party located each missing comrade. Gazef found the protagonist and his members of Darkness, bringing the bodies of Ramposa III and Brain Unglaus that he managed to recover. The Warrior Captain then took the bodies back through a Crack, to return them for revival. Shortly after he left the protagonist and his adventurer team met Enhela Read Gahi who was searching for his own comrades: Nigun Grid Luin and Ian Als Heim.

There the members of Darkness learned from Enhela that the reason as to why the protagonist and Enhela were able to survive in the realm was due to being born from the Sea of Possibilities by their creator the Devourer of the Nine Worlds. Enhela attempted to have the protagonist come with him to fulfill his purpose, but was driven away by the attacks of the Pleiades who were hiding.

The revelations that the protagonist was not an actual creation of the Supreme Beings but an idea was troubling for Nazarick, with many of the Floor Guardians agreeing that the protagonist could no longer stay in the dungeon. However they and Momonga were unable to fully cast the protagonist out as he was still a part of the legacy of the Supreme Beings and held fond memories of him as their comrade. Ultimately as the protagonist was now a target of Enhela, Momonga forbidden the homunculus from returning, but allowed him to retain his post as Territory Guardian of E-Rantel.

There in the city, the protagonist met with Gazef Stronoff along with Enhela at a meeting of the representatives of the Tripartite Alliance, where they shared information, omitting certain facts. Upon the news that there were still people on the other side in need of saving, a rescue operation known as the Four Kingdoms Recue Team was then organized by the factions to rescue those trapped on the other side. Part of the expedition to save the people included the members of Darkness, Blue Roses, Gazef, Brain, Nimble, Leinas, and the newly returned Ian and Nigun.

Unknown to the expedition, the number of people they needed to rescue was reduced significantly by Soi, who retrieved several people in order to make it less suspicious that Climb, who was previously captured by Nazarick, was a missing among those on the "other side". A hundred people were rescued by the expedition before forcing to retreat after encountering a giant horde of Chaos Beasts.

Layout
The Chaos Zone manifests as a crack in reality leading to a void-like dimension filled with purple-blue fog where many monsters lurk. On the "other side", the appearance of the dimension makes it appear no different from the locations of the New World. As it contains locations containing soil and trees, however nothing is what is appears as the forests are devoid of animal life. There are ruins and yet no signs of actual civilization. According to the protagonist who was trapped there for a time, the Chaos Zone normally has no distinction between top, bottom, left, and right. In fact the current appearance of a location may simply just one of the “shapes” people can recognize based on the many “possibilities” that exist there.

Additionally the movements of the celestial bodies that appear in the sky differ from the normal sky, as it could appear night in the "other side" while day in the New World. Time also moves quite differently, and thought the exact difference is unknown, it seems that on the "other side" where a single day can be spent, months in the New World pass.

Activity in the zone is extremally limited to those not native to the world. Once visitors are in the zone, they fall unconscious. The phenomena is termed the "chaos environment", and it affects not just living beings but even non-living beings such as automatons and undead. Under the adverse effects of the world, no one, save for Chaos Beasts and Contaminated Beasts are able to function.

The zone serves as a special event zone and periodic occurs in the game at designated times:

Times

 * March 13, 2019 @ 3:00 PM
 * April 19, 2019 @ 3:00 PM
 * May 8, 2019 @ 3:00 PM
 * June 12, 2019 @ 3:00 PM
 * August 19, 2019 @ 3:00 PM
 * September 12, 2019 @ 3:00 PM
 * November 20, 2019 @ 3:00 PM
 * January 5, 2020 @ 3:00 PM
 * April 10, 2020 @ 3:00 PM
 * June 12, 2020 @ 3:00 PM

Trivia

 * The Chaos Zone allows players in the game to acquire point rewards and ranking rewards by accumulating event points that can be earned by completing quests.
 * In a special game event, the Takemikazuchi Shrine was created within specialized Chaos Zone.
 * In a chapter of the main story of the game, the visual of the Chaos Zone was reused as the setting for the world created by Depiction of Nature and Society.
 * Besides Chaos Beasts and Contaminated Beasts, there are three ways to move in the Chaos Zone without any ill effect:
 * One is by wearing adaptive equipment like those made by the Sorcerer Kingdom using Chaos Stones. However the equipment must be constantly replaced, or the user will succumbed to the effects of the world.
 * Second is to be infected by the miasma and turn into a Contaminated Beast and then detoxified which allows a user to develop an immunity to the environment.
 * And lasty, as shown by Enhela Read Gahi, who claims that it is due to being a God-kin apparently grants one a natural immunity. Though his affiliation of being a God-kin is more related to being a creation of the Sea of Possibilities as is the protagonist.
 * To fool Gazef and explain how the protagonist was present in E-Rantel, actually a doppelgänger, and in the Chaos Zone, where the real one was trapped; the protagonist lied by saying that he was sent into the past after he left the realm to the point when the disaster that struck E-Rantel with multiple Cracks appeared and blamed it on "time paradox".