Hidden Floor

The Hidden Floor (숨겨진 층, Sumgyeojin Cheung) is a fake, imaginary, unreal data world located inside the Hell Train. Only the Regulars who have cleared the entire Hell Express can leave their data in the Hidden Floor. People who have clear the train and entered the hidden floor will be called as "Warriors" and will be guided by wandering minstrel and record their adventures.

About
To gain an access to the Hidden Floor, Regulars must cleared the entire Hell Express. All regulars who succeed to do so, will be given a privilege to record or save their data, (this "data" means about all regulars' personal details such like name, appearances, personalities, abilities, life history and biographies, etc) in the train's system. This "data" will remain in the system and create some kind of Artificial Intelligence (A.I) life which all come together to form The Virtual Floor. These Virtual Floor "does not exist in reality" within the tower.

There are two ways to enter the hidden floor.
 * Physically: Entering the hidden floor physically means that you enter normally with your "real body" as a "living being". Although the hidden floor is a fake, imaginary world, you will still experience real injuries, real pain, bleeding, and the worst case scenario, you can "die". Entering physically also means you can't enter in a normal way. You have to be able to gain access to enter the "main door" of the hidden floor that was hidden inside the hell train. These main door cannot be destroyed even by a ranker like Karaka. This door is heavily locked and can only be opened by using Master Key. There are two master key, one is currently in the possession of King Zahard and the other in the hand of Hell Train conductor.


 * Non-Physically: Entering by non-physically means that you didn't enter the hidden floor with your "real body" as living being. Your real body will have to continue to climb the tower. You won't experience the hidden floor, what it would look like, what are in the inside, because you're not there 'physically'. The 'system' will use computer projection to create a fake body and image of yourself and it will 'artificially' live inside the hidden floor. In other words, it's not the "present you" but more like the "past you".

Rules
There are several rules on the hidden floor.
 * 1. Anyone who reveals the details about the existence of this floor to the outside will lose both their data and their memory about hidden floor.
 * 2. Once you can become a ranker, only your data remains and you cannot enter the floor again. In other words, ranker or high rankers cannot enter the hidden floor.
 * 3. Once you have cleared the train, you cannot update your data or bring any items or goods obtained in that place outside the floor.

Exceptional Rules and Condition
 * As one of the Family Leaders. Po Bidau Gustang was exempted from some of the rules, but his status as high ranker still forbids him to enter the hidden floor.
 * Zahard manage to break rules No.2, despite his status as high ranker, by transferring part of his present self-data to enter the hidden floor through two special mirrors device (one mirror was sent to Baam and another one was used to confront Yellow, Ha Yura, Icarus, White and Data Urek.
 * Ja Wangnan manage to break rules No.3 by bringing a mysterious weapon like dagger to the outside. The weapon can talk and has a self-awareness.
 * Treasure Eating Stingray manage to break rules No.3 by bringing Zahard's special bracelet to the outside. The bracelet seems to be a real items from the outside that was stored inside the hidden floor by Zahard.
 * If regulars haven't finished clearing the Hell Train, you can still enter the hidden floor by using the special item Master Key. People who used this method cannot save their data in the hidden floor.

History
After going through Revolution on the Hell Train, Zahard sensed that he will become a godlike being, so he sought to preserve his "human" self. When one of the disciples of The Workshop found out about this concern of Zahard, he gave Zahard the Mirror of the Past as a gift. That mirror has the ability to store a person's present self within it. Upon hearing this, Zahard was so happy and immediately 'store' himself in the mirror.

After Zahard stored his image using the Mirror of the Past, several of his companions did the same. The Future King of the Tower left the Mirror in the last room on the Hell Train, so that only those who clear the Train may see the world within the Mirror.

When Zahard became the King, his fame soared and many Regulars left their data in the Mirror to meet younger version of the King in this artificial world. The disciple of the Workshop found out that the data were living inside the mirror, creating their own world. The disciple decided to protect that world and the Spell of Oblivion was placed on the room with the Mirror of the Past. Whenever someone who stored himself in the Mirror trys to reveal anything about that place, they forget everything about it. The Disciple also created a single door to that new world, along with only two keys. He gave one key to Zahard and another to the conductor of the Hell Train. After hearing what had become of the Mirror of the Past, Zahard was amused and is said to have called it the "Hidden Floor".

The Hidden Hidden Floor
Inside this virtual world, data Zahard and his companions grew tired of the huge increase in the numbers of newcomers. With the help from the outside, the Hidden Hidden Floor (숨겨진 숨겨진 층, Sumgyeojin Sumgyeojin Cheung) was created using another Mirror and data Zahard transfered there with only a few chosen.

Stages
The Hidden Floor consists of various stages. To advance to the next stage, the participating Regulars needs to complete the quests. To begin the quest, you have to activate the "quest screen". Completing quests will fill the gauge on the Good and Evil Monitor with "white color". When the gauge bar is completely filled with white color, the Big Breeder will give the main quest to banish the Fruit of Good and Evil.

Data Yu Han Sung found out that by filling the gauge "black color", instead of "white color", on the Good and Evil Monitor, Regulars can get the special Hidden Grand Quest, which also leads to the next stage.

List of known Stages
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Location

 * Quarantine Area
 * Treatment Plant for 'Quarantined Elements'
 * The Beach where Khun and Hockney landed

Fruit of Good and Evil
Fruit of Good and Evil (선악과, Seon-aggwa) is a quarantined place for the most dangerous individuals in the Hidden Floor. Batis was imprisoned here for going against the Big Breeders.

If Regulars in the Hidden Floor live a life that is evil, the giant eats the fruit and breaks out of his shell to punish them. However if they do good things like completing quests, the giant drags the fruit into the underworld. Regulars who achieve that can advance to next stage.

Bug Room
Sometime during his climb of the Tower, Urek Mazino visited the Hidden Floor. He promised the Big Breeder that he will not cause trouble, but when he is later informed that his data self will be unstable due to trouble in saving his data, Urek smashed the mirror in anger. This caused bugs, such as the continued existence of Urek's sworn enemy, which was supposed to disappear after Urek left. The sworn enemy is also weakened, compared to Urek. The bug also caused changes in the Hidden Floor, causing the artificial data humans to become more human-like than they should be.

One of the Big Breeders isolated these bugs into a room, dubbing it the Bug Room.

Data Human

 * Batis
 * Medley
 * Mi-eum
 * Rose
 * Dee

Data Regular

 * Khun Eduan
 * Khun Icardi
 * Khun Marco Asensio (Data)
 * Khun Maschenny Zahard (Data)
 * Yu Han Sung (Data)
 * Zahard (Data)

Shinheuh

 * Goliath: A green giant turtoise that can standing and walking with his two foot.
 * Giant Snake Divine Sea Fish

Others

 * Big Breeder
 * Sworn Enemy
 * Hidden Floor Soldier

Notes and Trivia

 * The Hidden Floor is ruled by Big Breeders. They are comparable to Guardians.
 * The Hidden Floor is inhabited by data of Regulars and artificial data humans.
 * Every Regular has a Sworn Enemy generated, based on their past.
 * Regardless, the Floor of Death and the Hidden Floor is like a 2 for 1 set of arcs. They are leading into the thick of the plot perhaps as well. And in this arc we will get to see more of the characters that didn't get spotlighted in the Floor of Death.
 * SIU has stated that this arc is based on a popular trope of "living inside a video game" found in many light novel and manhwa that swept across Korea and also recently across Japan. However, he is focusing less on game-like aspects but more on the virtual reality. So the characters from this arc are less game characters but more of a virtual organism, a human composed of data, that's the idea at least. So he's skipping the usually used concepts such as items, skills, status effects and the like for this arc for added realism.
 * This arc is based on RPG games "Hero Legend Series" or "Ustonicia Story".
 * Although SIU has said this arc is loosly based on the "video game is reality" genre, the plot and theme will be much more Cyberpunk in nature. In addition, there will be a few stories about some characters pasts or the Ten Families or the Tower itself.
 * SIU also think about the Sworn Enemy system, while serving a narrative role of "balancing this world", can also tell a great number of stories.
 * Since the Hidden Floor arc has similar themes with the Floor of Death, a lot of the lore and the central themes will be similar.