Shinsu

"Shinsoo... Is the very oxygen we breathe in The Tower, and almost everything is Shinsoo itself" - Yuga (Ren )

Shinsoo is a miraculous substance that flows through the Tower with higher density on higher floors. In different time Shinsoo can become water, fire, light or one of other endless list of variations. Shinsoo is something you cannot ascribe any special property to.

Shinsoo is essencial for living, it allows breathing and provides moisture.

Controlling Shinsoo firsthand is a very rare ability, and it is essential for being a Ranker. Basically all 'Regulars ' have some abilities for manipulation, but not all of them can do it proficiently.

Shinsoo can be very deadly. Almost all regulars and rankers use it to fight. Wave Controllers specialise in using it, but all positions have to learn it eventually in order to climb successfully. Irregulars have a special talent for using it.

Air and Shinsoo
Must research in the difference between air and shinsoo is made by Ashul Edwaru, and the below is a summery from a book about weapons that he has made.

First, the common point is that they both let beings breathe. And they both flow constantly. It is also identical that they are powerful enough to threaten others when they flow harshly.

Then the difference? The biggest difference is indeed the characteristics by the concentration. In Shinsoo's case it's more like a gas when it's in low concentration and more like liquid when it's in high concentration. But it seems air is not liquefied even in high concentrations.

The second difference is the circulation. The circulation of Shinsoo is very fluent but there is no common law. (And the movements are all different by the floors of the Tower.) But it is said that there are set laws in the circulation of air. (I want to study some more about the laws, but the research is slow because none of the irregulars that I have met is knowledgeable enough about the laws of air)

The third difference is consumption. Shinsoo exists everywhere inside the tower. So Shinsoo exists even in a room that is completely sealed. Shinsoo does not flow in from somewhere else, but is rather created from the Tower. So, we can live in the sealed places. Air is not created from sealed places, and if a being is locked inside a sealed room, the being will consume all of the air and die. (It seems very uncomfortable.)

He end by saying that the readers might find it strange that he start a book about weapons by speaking about shinsoo. But that only means that they are ignorant about how weapons in the tower funktion and is made.

Manipulation of Shinsoo
The act of handling Shinsoo externally to change the surroundings or to attack the opponent is called Shinsoo manipulation. It's also called Sooyuk(水役-Water handling) and Poongsul(風術-Wind skills) by some organizations or regions. The first person to systematically organize the data of Shinsoo is Bedur Goostang, one of the heads of the 10 Families. All words and units about Shinsoo that are commonly used are from his books.

There are two ways to manipulate Shinsoo: using an item or manipulating it firsthand. In the Tower, when people say they manipulate Shinsoo, it generally means the latter.

Shinsoo manipulation ability varies by individual, but the children of the 10 Families are likely to be born with outstanding properties. The same goes for many of the families that are derived from the 10 Families. Some unknown families protect their bloodline in secret, keeping the ability for generations.

The Contract
In the Inner and Outer Tower, if people wish to control Shinsoo without items they must have a contract with the Guardian  of the floor. Items are only usable when it's under contract with the Guardian (For example, an item that is under contract with 2-30th floor Guardians cannot be used on the 31st floor.).

Even when you make a contract with the Guardian, you cannot manipulate Shinsoo in all areas of the floor.

After making a contract with the Guardian, people must abide by some limitations. If somebody doesn't abide by the limitations, the Guardian considers the contract to be violated and breaks the contract. The level of limitations varies by the contract class. For Rankers and High Rankers there are almost no limitations.

It doesn't mean you cannot manipulate Shinsoo at all without a contract. Even when the contract is not made, some simple manipulation is possible. And the inborn resistance to Shinsoo or body augmentation/strengthening using Shinsoo is a power that exists naturally without a contract.

In the current floors, there is only one place that you can control Shinsoo without a contract. And that is the Forty-Third_Floor, because it no longer have a Guardian.

Those born into one of the 10 Great Families or some of there derived families can manipulate Shinsoo without special contracts. That doesn't mean they do not make contracts with the Guardians. They are 'under contract' the moment they are born.

Baang, Myun and Soo
The basic unit of Shinsoo manipulation is called Baang(放-room) and the size of the Baang is called Myun(面-side) and the density of Shinsoo that goes in a Baang is called Soo(水-water).

Baang
The basic unit of Shinsoo manipulation.

The more Baangs people handle, the more highly skilled they are evaluated to be in Shinsoo manipulation. But to handle many Baangs doesn't mean people can handle bigger Myun and Higher Soo. The more Baangs there are, the harder it is too control them. Operating Baangs by force may overload the manipulator's body and mind, even causing death in serious cases. If cases of the support of a Lighthouse, the manipulation of Baang that are materialized may be easier, but the number of Baangs do not increase.

Myun
The size or areal of a Baang.

Regardless of the height, it only means the area of spread Shinsoo, and the numerical value by unit is the same as pyeng. (*坪:A land unit. 1 pyeng nearly equals to 3.3 square meters.)

The reason why people do not consider the height when they calculate the size of a Baang is because the height varies greatly by the circumstances and it's hard to assort them accurately. (In case of the height, people convert the numerical value by the density to calculate, but they do not substitute the number to the size of the Baang.)

The larger Myun people handle, the possibility of Shinsoo application gets higher. But handling large Myun doesn't mean they can manipulate a certain density of Shinsoo on the Myun. It's general for the density to decrease from the center of the Myun to the edge, but in the case of an outstanding manipulator, it's possible to make the density of the edge thicker. There are cases that can freely manipulate the density of the Baang, but they're very rare.

Soo
It means the density of Shinsoo that is given inside the Baang. It's calculated by the point where the density is the highest. There's no comparable unit on Earth, and the measurement is done only by the Lighthouses, Observers and the acute senses.

Higher Soo means stronger effect and destructive power of Baang, so it's very important to handle high Soo. The limit of Soo people can fill in a Baang differs by individuals, and it has nothing to do with the surroundings. Even in a Baang, Soo is not constant. The numerical value of Soo changes by Myun and it varies greatly from person to person. If the manipulator can concentrate well, he can handle Shinsoo of many Soo in the small Myun and when he's good at distributed processing, he can handle a certain quantity of Soo in a lot of Myun. Of course there are opposite cases.

Baang, Myun, and Soo
When poeple basically say Baang, Myun, and Soo of an individual, Baang is number of Baangs the manipulator can handle the most once, and Myun is the biggest Myun he can handle when he made a Baang. And Soo is the highest density he can put in when he made the Baang, regardless of Myun.

If someone can handle 4 Baang once, and can handle 100 Myun when he made one Baang, and the most higher number of Soo he can gain in one Baang is 30, he can say that he can handle '4 Baang 100 Myun and 30 Soo'.

Baang, Myun, and Soo are in close relationship together, and they vary a lot by the support of the Lighthouses or others.

Generally, when the number of Baangs increases the Myun and Soo that can be handled decreases, and when the number of Myun increases, Soo decreases. And Soo changes by the number of Myun and Baangs. Basically this tendency is called 'Minus tendency'. Sometimes there are diathesis that when the number of Baangs increase the number of Myun and Soo that can be handled also increase. This is called 'Plus tendency' and it's a very rare ability.

Even the Minus tendency can revise the minus numerical value by a long period of training and support. But it can't be turned into Plus tendency.

And even being the Plus tendency doesn't mean he can create infinite Baang, and when the number of Baangs increases, it's the same that it gets harder to control them.

Until now, the person who have handled the largest numerical value of Shinsoo is Enryu. And although the accurate number is not recorded, it's clear that it surpasses other recorded figures greatly. (According to a Light Bearer who could record Enryu's combat, Enryu is known to have handled more than 9000 Baangs during the combat.)