Disclaimer: All the characters appearing on this fic are not mine.

Hello guys, Caelus here. I know that I have some unfinished/ongoing works but I can't help mysrl but to write this idea. This idea has been with me for a long a while, discussing and sharing some thoughts with some friends through PM (thanks A Reincarnated Writer and Tsunashi777).

Anyways, this will be an AU fic showcasing Tatsuya Kishinami (yes that is his surname) being spared from the Articificial MCA operation and instead was exiled by the Yotsuba clan and had to live a life away from his sibling(s). During his exile, his Dad taught him about Magecraft, the World, and the Mysteries that encompasses all living and non-living things. Due to some alternate events, Tatsu is born 2 years early than canon, Miya and Honami are still alive, and Maya was spared from her tragic fate and have a child of her own.

And yes, this fic will have harem but the main pairings will be Tatsuya and Mayumi (Tatsumi).

This list of terminologies are the only thing I can write as of now (sorry, college stuffs) but I'll update as soon as I can find some breather from my tight schedule.

Another note, some parts of this will have characters watched some kind of video or a Visual Novel type of sorts like a Reading Fic.

Mystery (神秘, Shinpi ) is a sliver of power of many different types that comes from the Root. It is the source of all supernatural phenomena such as Magecraft or ESP , and beings such as True Ancestors , Dead Apostles, Servants, Spiritual Bodies, as well as Phantasmal Species show signs of Mystery. Mystery accumulates over time and grows stronger with age.

If two different types of Mysteries collide with one another, the stronger Mystery will overwhelm the weaker one. Certain items that have a long history and age can also show signs of Mystery, but if they are severely damaged, they will lose all the Mystery they have accumulated.

It is also possible for a human's body and soul to reach the level of a Mystery.

Authority (権能, Kennou ) is a Mystery possessed by the Gods, allowing for world construction, event shifting, time-flow manipulation, kingdom-building, and other such powers of that level. While normal skills "accomplish a certain task by following a corresponding principle", Authority works "simply by making things happen because one has that right." Though such powers existed six thousand years in the Age of Gods before the modern era, the advent of the AD calender relieved the gods of their duty of the advance of human civilization and retired them to the past.

Magic (魔法, Mahō ), also referred to as True Magic and Sorcery, is the highest class of Mystery that surpasses Magecraft and all current sciences of that age. It represents the actualization of events that are impossible to reproduce in a certain era, whether by humans or the planet, even if given an infinite amount of time and resources. It is considered the ultimate accomplishment of a Magus, and only within the grasp of those who have accessed the Swirl of the Root.

"Magic" can be differentiated from "Magecraft" in that the consequences of its use are ostensibly "impossible" or "miraculous." Concepts like time manipulation, teleportation, spatial warping and quarantine, and the resurrection of the dead are miracles thought to be possible only through the application of Magic.

Magecraft (魔術, Majutsu ), or Thaumaturgy is the artificial reenactment of a Mystery , a miracle. It is referred as "Ancient Magic" by the practitioners of Eidos' Thaumaturgical Theory.

Magecraft is the ability to bring about what is possible through science with supernatural means; although the process is considered a miracle, the end result is not. The limits of Magecraft have changed with time, as science evolved and Magic from the past became possible through science.

There is no impossibility for Modern Magecraft within the rules of the world, and with enough effort and time spent studying the appropriate school, anything within the limits of human intellect is possible. However, because Magecraft acts as the reenactment of Mysteries that already exist in the world, it is impossible for it to create new Mysteries; even with an infinite amount of research, there is a "wall" that prevents the wisdom of humans from doing so in the current era. The realm past this "wall" is known as Magic.

Psychic Power (超能力, Chō Nōryoku ), also referred to as Extrasensory Perception (ESP), is a catch-all term to refer to the circuits that cause supernatural phenomena to occur. It is a form of nature interference that to the psychic comes as naturally as breathing. Unlike Magecraft, which can be taught and practiced, inherent ability is an absolute necessity. Psychic powers are the ultimate ability of humans , who have become an existence independent of nature. However, these powers are generally incomparable to the great abilities possessed by Demons or Mixed-Bloods . In the end, they are only human.

Psychic powers only appear by chance and are limited to one generation. Generally, a psychic is born with both a "normal" perception that allows one to function in society, as well as an "abnormal" psychic perception (extra channel); those who only possess the latter are known as an Unfit Existence (存在不適合者, Sonzai Futekigōsha ).

Codecast (コードキャスト, ) A Program: Simple Spell (簡易術式プログラム, ) is a Thaumaturgical Foundation (魔術基盤, Majutsu Kiban) used in cyberspace and in the real world. A wizard writes and compiles the program code in advance, and activates it by passing magic through it. There are two types of Codecast. External Codecasts are one time use consumable Codecasts, while Internal Codecasts are installed into the body... or rather the Spiritrons structures [that make up one's body in cyberspace]. Codecasts that have been installed are very powerful, however seeing as they change the fundamental nature of the user, not many wizards choose to use them. Codecasts implemented through the use of a Mystic Codes fall somewhere in the middle [in terms of power and effects on the user]

Eidos (個別情報体, Kobetsu Jōhōtai), also referred as "Modern Magic" by its practitioners, is a newly created Thaumaturgical Foundation (魔術基盤, Majutsu Kiban) that simply overwrites an information body through the use of a Magic Sequence (魔法式, Mahōshiki). It refers to the modification of a target's phenomena by modifying its Eidos, hence producing its result. There are two planes – one physical (the physical plane is the real world as all humans perceive it) and one information (the information dimension is a representation of that world where each entity has a corresponding information body).

Eidos is not the "flinging" of spells through the physical plane, but the precise overwriting of a target's data in the information dimension. Each information body (Eidos) is composed of thought particles called Psions. Magic sequences used to overwrite information bodies are also composed of Psions. Only those that have a Magic Calculation Area in their brain can manipulate Psions to cast "magic".