Volume 1 appendix (Contain spoilers, do finish the story before reading it.)
List of world names that has meaning attached to it
«Aequinwelt» - The world that acts as the center of the universe. (Chapter 2 Part 4)
«Versteckwelt» - The 'other side' of the world (Nariaki's world, Chapter 2 Part 3)
«Aió̱nios» - Everlasting (Kanae's world, Chapter 3 Part 1)
«Tsunagu» - Connecting (Kazuki's world, Chapter 3 Part 3)
«Traugic» - Tragic added with an extra 'u' (Chapter 7 Part 8)
«Fasado» - Façade (Chapter 7 Part 12)
«Aufruer» - Uprising (Chapter 8 Part 15)
«Veloser» - Resolve spelled backwards (Chapter 8 Part 17)
«Etermin» - 'Determined' that has both beginning 'D' and 'ed' removed (Chapter 8 Part 18)
Denscrant eyes – Grant the user the ability to perceive visions from parallel worlds, and information about living beings.
Denscrants – A group that possessed the Denscrant eyes banded together. Traversing across parallel worlds, they protect the universe from their mortal enemy, the Doppelgangers. To return back to being a normal human being, they seek to extract their Doppelgangers' pyricore. If one passed away, all of his/her corresponding living parallels would cease to exist.
Aincrex – Short-hand for 'An Incarnating Existence'. Taking on a form similar to humans, their existence is a collection of every evil there is within a human being and its corresponding parallels. They are also responsible for causing the Unnatural Death phenomenon in all existing parallel worlds, for the purpose of extracting pyricores from normal humans to replenish their dwindling life force.
Doppelganger – An informal term used by Denscrants in place of 'Aincrex'.
Death by Fate – Also known as Natural Death. Occurs when a living being dies at their predetermined time of death under normal circumstances like illness and aging Fate has set out. Extreme cases like murder exist, but ultimately, the cause would be due to something or someone that originated in the same parallel world.
Death before Fate – Also known as Unnatural Death. Occurs when a living being dies before their predetermined time of death due to abnormal circumstances. Such occurrences could only happen because of an abnormality that doesn't belong in that parallel world in the first place.
Pyricore – It contains experiences, information, knowledge and memories that particular human had accumulated throughout his/her life. Basically, one would acquire everything about that person, along with his/her existence. Each and every pyricore contained the life force of a human being. Being the energy that acted as a continuum that unified the body and mind, all Aincrexes needed it to remain in their living state.