Magic

Currently, magic is rare and addressed with little research. Nobody has found anything that could confirm the existence of magic. However, based on old documents written by ancient mages, magic exists and explains our existence by assuming magic does exist. These ancient mages explained magic scientifically and sorted them into ten tiers.

Theory of Equivalent Exchange
All magic requires a sacrifice. According to Alexander Levian, magic without a sacrifice is impossible. He states, "magic requires a sacrifice; the stronger the sacrifice, the stronger the magic." Sacrifices can be anything. The common ones are classified into tiers of quality. In a war between the Lavenders and Avengeles, mages used their lifespan as a sacrifice. Depending on the strength of the magic they desired, they shortened their lives. Mages who knew that this was their final moment and were loyal to their country sacrificed their soul. A soul is the most powerful sacrifice and is catastrophic; sacrificing a soul means killing yourself and closing the doors to heaven and hell. Mages who sacrifice their souls enter the "permanent death" state which doesn't allow them to be revived for eternity.
 * Tier 1 - Abiotic resources such as rocks, wood, and water
 * Tier 2 - Biotic resources such as plants, trees, and animals
 * Tier 3 - Humans or their limbs
 * Tier 4 - Lifespan
 * Tier 5 - Souls

Theory of Magic Through Mana
Iwata Hashigoro derived a different theory of how magic works. He arrived at the conclusion that every living being has an energy which he calls mana. Mana is the energy of magic, and magic comes from the manipulation of mana. Mana can be replenished over time. What happens when a person's body is completely drained of mana is unknown.

Nomi Suzume added onto Iwata Hashigoro's theory of magic coming from mana. She insisted that mana exists in everything including the air. She later explained that most people know how to use magic through the mana inside them or by using another object's mana. Coincidentally, her theory agrees with the theory of equivalent exchange. According to her, equivalent exchange is merely the absorption and usage of mana from an object to create magic. Based on mere speculation, Nomi Suzume believed that if a person was able to use the mana in the air, they would be infinitely powerful.

Theory of Magical Output
132 years after Nomi Suzume's continuation Theory of Magic Through Mana, Simon Colon with his group of magic theorists concluded that every person has a maximum amount of magical concentration. Explicitly meaning a person can only use so much magic at once. This theory shut Nomi Suzume's speculation of "infinite power" and they concluded that a person who can use the mana in the air will have a little benefit which is almost negligible.  

Theory of Mana Dead End
The theory of mana dead end was an experiment conducted on slaves during the time Satan was still active. Jorel Simms forced these slaves to use all of their mana. When they came extremely close to no mana, they started experiencing hallucinations. When they finally lost all of their mana, they all practically exploded physically. Those who survived were unable to ever use magic again.

Azwu Khalil proposed the idea that Satan became inactive because he used all of his mana and as a result physically exploded. If he survived, he does not have a human form and might be waiting for a new host.

Theory of Magic Tiers
The Theory of Magic Tiers was proposed by Doctor Vadictan G. Baxell. He proposed that all magic can be classified into ten tiers, with the first being the weakest tier and tenth being the strongest. Tiers 6 - 10 are all theoretical tiers. These tiers were added when Doctor Vadictan tested a devil. He claimed that this devil could easily lead the world to destruction.
 * Tier 1 - 3: Elemental Magic (fire, water, wind, earth) and Ninjutsu
 * Tier 4: Dark Arts, these skills include reviving the dead and potentially damage the caster
 * Tier 5: Shapeshifting, Aura Manipulation, Supernatural Physiology, Enchanted Condition, Sealing
 * Tier 6: Dimension Manipulation, Life Manipulation, Teleportation
 * Tier 7: Molecular Manipulation, DNA Manipulation, Mana Manipulation
 * Tier 8: Reality Warping, Time Manipulation, Energy Manipulation, Gravity Manipulation, Life Creation
 * Tier 9: Creation, Destruction, Universe Manipulation
 * Tier 10: Unknown

Theory of Magic Affinities
Every person has an affinity towards a certain type of magic. There are six affinities: Fire, Water, Wind, Earth, Dark, and Light. Some magic sit in a category outside of these affinities.

Every person has at least one affinity towards a type of magic. When one person has an affinity towards a magic, he or she has the ability to use magic under that category. For example, a person with a natural affinity towards Fire can use fire abilities. There are some cases where a person has multiple affinities. Though, it is a very rare phenomenon.

It is impossible for someone who doesn't have an affinity towards a particular type of magic to utilize said magic. The chance of someone having multiple affinities is shown below:

y = probability                                                                                                                                                                    x = amount of affinities This equation will return the probability of getting that amount of affinities.

Parts of Magic
All forms of magic are composed of different components which combine and create said magic. Magic can be conducted by the use of a transmutation circle, a magic circle, hand signs, or tools such as wands and books. A spell can be manipulated by modifying the magic sequence. A spell's properties such as duration, direction, area of damage, etc. can be altered. The basic idea behind magic creation is the concept of creating and connecting a magic sequence. The creation of magic is often difficult and dangerous that it's usually forbidden unless you have direct permission from the ruler of your country.

Forbidden Magic
All magic above tier 4 is forbidden unless stated otherwise. This is to keep the world safe from the dark side of magic, given that magic was created by Satan himself.

State of Magic Today
Through the years, details on the utilization of magic were lost, leading the world today to believe that magic does not exist. Magic suddenly stopped working over a thousand years ago which is reported to be when the gods were at war against Satan. Because of this, many scientists believe that magic will come back in production whenever Satan comes back.