Hidden Floor

The Hidden Floor (숨겨진 층, Sumgyeojin Cheung) is a fake, imaginary 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 cleared 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.

Although the concept of the hidden floor is a fake, imaginary world, you still enter normally with your "real body" as a "living being". In other words, you will still experience real injuries, real pain, bleeding, and the worst case scenario, you can "die".

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
There are several special cases where the rules are broken:
 * As one of the Family Leaders, Po Bidau Gustang was exempted from some of the rules, but as a High Ranker, he is still incapable of entering the Hidden Floor again.
 * Zahard, despite being a High Ranker, was able to install a failsafe that would allow him to project himself into the Hidden Floor anyway should the scale be destroyed 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 (broke 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 (broke 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.

Entering The Hidden Floor
There are two ways to enter the hidden floor.

Main Door
Entering the hidden floor through the Main Door means that you enter in an 'unusual way'. Because normally, you will enter the hidden floor in a way of 'saving your data' after clearing all the hell train test. However, entering through the main door means you don't have to clear all hell train test, but you can't save your data.

This Main Door is located inside the hidden room called "The Room of Time Past" within the hell train. This door cannot be destroyed even by a ranker like Karaka and won't open no matter what he do. The door apparently seems big when seen from the outside, but turns out, it's nothing compared to when it was seen from the inside. From inside the hidden floor, the main door is so huge and was seen floating above the sky in flat-down horizontal position.

Looking at the door from the inside view, you'd think people who enter it will directly fall from the sky, but you got it wrong. You will be directed to an imaginary dark space first where the Mirror of the Past will do a security check upon people who enter through the door, screening their past and decide where you should go to. Depending on the mirror's decision, everyone will likely end up in different place. So you won't fall from the floating door on the sky only if the mirror decide you're not supposed to be there.

This door is heavily locked and can only be opened by using the Master Key. To be able to gain access to enter this "main door", you should obtain just one of the two master key. One key is currently in the possession of King Zahard and the other key is in the hand of Hell Train conductor (Currently, the Master Key of Hell Train conductor was stolen by Gustang and given to Baam).

Normal Way
There is a normal way to enter the hidden floor. It is said, you will be able to enter the hidden floor after clearing all the hell train test. However, there is no clear information about how these method work.

After you embark on journey inside the hidden floor as a 'real living beings' and completing quest missions, it seems that the 'system' will use computer projection to create a fake body and image of yourself and it will 'artificially' live inside the hidden floor forever.

History
After going through Revolution on the Hell Train, the real young Zahard sensed that he will become a godlike being in the future, so he sought to preserve his "human" self. When one of the disciples of The Workshop found out about this concern of young 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, the young Zahard was so happy and immediately 'store' himself in the mirror. After Zahard stored his image using the Mirror of the Past, he also invited his 12 best friends and several people that he trust to also stored their image within the mirror. The young Zahard then left the Mirror in the last room of the Hell Train, so that only those who clear the Train may see the world within the Mirror.

After the real Zahard became the King of The Tower, the disciple of the Workshop found out that the data that were living inside the Mirror was creating their own "virtual world". The disciple decided to protect that virtual world and then placed the Spell of Oblivion on the room with the Mirror of the Past in it. Whenever someone who stored himself in the Mirror trys to reveal anything about that place, they will forget everything about it. The Disciple also created a single door to that virtual 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".

When the story about the Hidden Floor started to spread in the Tower, many Regulars have been taking the Hell Train route and tried to finish all Hell Train test as the requirement to enter the Hidden Floor, so they can left their data in the Mirror and meet younger version of the King in this artificial world. Many outstanding regulars managed to succeed, but many regulars also have failed.

The Hidden Hidden Floor
The Hidden Hidden Floor (숨겨진 숨겨진 층, Sumgyeojin Sumgyeojin Cheung) is another data virtual world aside from the Hidden Floor. Hidden Floor was first intended as a virtual world within a mirror, created by Zahard in order to preserve the young version of himself from when he cleared the hell train. After that young Zahard and his companions became data and created a world of their own. But following that, data Zahard and his companions grew tired of the huge increase in the numbers of newcomers data humans in the hidden floor. They wanted to separate themselves from them.

With the help of someone from the outside who brings another mirror and had the two mirrors face each other, the Hidden Hidden Floor was created. After that data Zahard transfered to hidden hidden floor with only a few chosen people.

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 meter on the Good and Evil Monitor with "black color" instead of "white color", Regulars can get the special Hidden Grand Quest, which also leads to the next stage.

Stage 1: Town of the Wandering Minstrel
Town of the Wandering Minstrel is a place that will welcome all The Warriors who have cleared the hell train. All warriors who entered in normal way to the hidden floor will be summoned here. This village was lead by the village head Rose.

Stage 2: Cold Land

 * Cold Land Stage - Quest Scroll Monster: Dragon: A dragon will appear in the flower to give "The Warriors" quest to defeating Cold Land Stage.

Hidden Stage 2: Sweet Castle
TBA

Stage 3: Rough Land
TBA

Hidden Stage ?: The Palace of Spears
This place is the main residence of Data Eduan inside the hidden floor. Not every Khun Family regulars data can visit this place. Only Eduan's favorite child can visit the Palace of Spears, they are Data Maschenny, Data Asensio, and Khun Icardi (Data).

Stage 7: Labyrinth of the Minotaur
TBA

Stage ?: Town the Golden Dome
Town the Golden Dome is a place within the hidden floor. This is a town full of artificial robots. The structure of this town was so unique that it has only one pillar beneath it as a foundation to make it stand. There is a golden dome right in the middle of the town, it is not known for what this building was built for, nor about it's use, purpose, and benefits. To access this place, the hidden floor adventurers have to aboard several wooden floating boats, as the media of transportation to across. The boat was so similar to gondola or canoe boat. The boat was navigated by the many eyed race, "Da-an Tribe".

They arrive at the town called the Golden Dome, where Rachel notices the presence of someone. She quickly precedes to excuse herself to look for this person that she thinks might be Ha Yura. The rest decide to split up to look for the rest of their companions. Baam ends up alone inside the dome, where an Data Zahard confronts him. Rak Wraithraiser notices that something is wrong a rushes towards Baam. Baam does not know who is in front of him until he introduces himself as Zahard.

Stage 21: Seed
TBA

Extra Stage: Training Stage
TBA

Hidden Stage: Glitch Room
TBA

Good Deed Points
Good Deed Points are points that will be received by 'the warriors' after they can defeat a 'villain' and complete the quest. If you can gather enough good deed points, you will filled the Good and Evil Monitor with white bars indicator or white light. The "Big Breeders" will give you the scroll for the "main quest" where you banish that Fruit of Good and Evil to hell.

Fruit of Good and Evil
Fruit of Good and Evil (선악과, Seon-aggwa) is a legend passed down by Big Breeder Chung from a very long time ago, right after these "Big Breeder system" existed. It was a lie spread between Data Humans as Big Breeder Chung's attempt to hide the real truth of the hidden floor as ordered by Data Zahard. According to Chung, he was ordered by Lord Zahard himself to hide the real truth of the hidden floor and to tricked the newcomers, doing useless things like completing stage. The legend said "If Regulars who entered 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."

Quarantine Area
Any Data Humans, Data Regulars or even real living beings who tried to break the rules, doing bad things, etc. inside the hidden floor, will be "arrested" and "quarantined" inside the "Fruit". Inside the fruit, the quarantined people will live or took refugee in the shelter called "The Seed". Once you were quarantined, it means you will be trapped forever and can't escape. The only way to escape is to open the Special Door inside the quarantine area.
 * Batis and Data Yu Han Sung was imprisoned here for going against the Big Breeders. They have repeated death and failure countless times in the quarantine area.
 * Twenty-Fifth Baam got arrested by Mirror of the Past when it screened Baam's past memories. Mirror of the Past was so shocked when it was unable to find any of Baam's past memories, then commented "You don't have a past?". The mirror quickly labeled Baam as "dangerous" individual for the hidden floor and arrested him.

The Fruit is actually the giant metal ball like object that is located in the palm of the hand of the giant human monster statue while the Monster Statue itself is only act as a "guard" to prevent quarantined "data" or "prisoners" from escaping and serve as an executor to kill them. The "Fruit" or "Quarantine Area" is a quarantined place for the most dangerous individuals in the Hidden Floor. To put it simply, this is a "Prison". At first, this place indeed was intended as a prison, but after Batis humiliated Big Breeder Chung with his song and uncover the real truth of big breeder, light up the fire to rebel in people's hearts, and make them started to fight for freedom, Big Breeder Chung was flustered and immediately changed the settings of this quarantine area, creating rules and requirements, making "The Warriors" (regulars who come into hidden floor) to complete fake quests so that the requirements fulfilled and the giant monster statue will "execute" the quarantine area, either destroying it or trapping it in the underworld until the next new warriors come to the hidden floor.

This quarantine area might seemed to be built for the good purpose, but it's actually a way for Big Breeder to get rid and "execute" everyone who tried to rebel and might threaten the hidden floor, including normal criminals or those who tried to enforce real justice and uncover the real truth of hidden floor and the evil acts of Big Breeders.

Special Door
There is one and the only way to "escape" from the quarantine area, that is through a special door. This special door was found by Data Yu Han Sung in all his life and journey as a Data Humans in the hidden floor after experiencing many adventures and deaths with Batis and other 'quarantined data human'. When Hansung first found the door, he and other quarantined data humans tried to opened it, but the door cannot be opened at all. Hansung also tried to destroy the door with his Shinsu attacks, but the door remains intact. It was revealed later by big breeder Chung that the special door has been set up so that no ordinary person can open or destroy it. According to Chung, the only way to open the door, is to use a special, exclusive technique that only Zahard and his companions used. Chung himself didn't know about the special technique, he just know that it belongs to 'Zahard and his friends'. That technique was later confirmed to be "Shinwonryu", after Baam can open that special door by using Shinwonryu, a special technique that only exclusive for Irregulars after they received 'Revolution' by the "God" of guardians, so this explains why Yu Han Sung and other quarantined data humans can't open or destroy the door.

Villains
Villains are quest monsters which has to be defeated by The Warriors" on their journey and adventures in the hidden floor. These villains has alphabet levels or grades (A|B|C|D|E) from weakest to the strongest.

Villains are summoned through the Villains Scroll. When the quest begin, a villain monster will appear in a certain spot. And if you defeat that 'villain', you complete the quest and receive "Good Deed Points". Here's the following list of the villains:
 * Armored Armadillo: According to Snake Charmer's analysis, this is an extreme defensive villain whose skills are focused more on Shinsu resistance and defensive than on attack power.
 * Giant Cyclops Monster: A monster who was summoned by big breeder Chung via the eggs of Mother Long-Tailed Tit villain.
 * The Chrome Cutter (B-Rank), "Champion Villain" of The Sweet Castle Stage.
 * Octopus Kim (C-Rank)
 * Hidden Floor Giant Rats
 * Mother Long-Tailed Tit (D-Rank)
 * Screaming Plants (E-Rank)

Champion Villains
Champion Villains are separate villains that must be defeated by The Warriors in the "Grand Quest". Champion Villains are summoned by the Big Breeders themselves. The Champion Villain is stored within a scroll which only Big Breeders have. It varies from stage to stage, but it's very powerful.

It seems that there are nothing such as "fixed champion villains" and the Big Breeders can pretty much summon any 'normal villains' to become 'champion villains', as seen when Big Breeder Chung purposely summon the weakest villain in the hidden floor: Mother Long-Tailed Tit for Khun's group to defeat so that Khun's group will kill Baam and Androssi quickly.

Villains Scroll
Quest Scroll is a scroll that store all data of the villains in the hidden floor. This scroll was used to summon monsters for the warriors to defeat. To access a scroll and summon the villains, you have to scan the scroll "barcode" by using Good and Evil Monitor which functioned as the "barcode scanner". When you scan the scroll barcode and push the button on the right side of the Good and Evil Monitor, the quest will begin immediately.
 * Town of Wandering Minstrel - Quest Scroll Archive: Quest Scroll Manager "Jyong"

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.

The "King's Cradle"
A mysterious room within the Hidden Floor. Wangnan entered here when he entered the hidden floor, as this was where the scale sent him when he entered the Hidden Floor. The Big Breeders Hwang and Jeok were surprised when they found out someone had entered the cradle, and said that someone who could do that was "clearly not ordinary". According to the Mysterious Weapon, it was the one who managed to pull Wangnan into the cradle.

Data Human

 * Batis
 * Medley
 * Mi-eum
 * Rose

Data Regular

 * Khun Eduan (Data)
 * Khun Icardi (Data)
 * 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 Soldiers

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.