Earth

The Earth in Seraph of the End is physically identical to the Earth of the real world, where there is the addition of largely vampire, demon, and seraph forces affecting events that take place there. Real world locations such as Japan are focused on in the story, down to cities such as Shibuya and Nagoya. By present times with Earth having been devastated by a calamity and claimed by vampires, human forces such as the Japanese Imperial Demon Army seek to regain control.

Society
Pre-catastrophe, the Earth's history progressed to the point of the early twenty first century. Where it had large cities formed, there was large numbers of people experiencing everyday life for them. Technology was featured in some societies including vehicles and aircraft.

For people being groomed for power within Japan, in attending First Shibuya High School, students there would have experienced more of the established world as it was even with the unconventional study methods used. Both spell craft organizations and a politically based family house system permeated society in parts.

Organizations

 * Emperor's Demons
 * Order of the Imperial Demons
 * Hyakuya Sect
 * Hīragi Family
 * Progenitor Council

History
Cretaceous era dinosaurs have been observed to have existed in Earth's prehistory. There were intelligent beings existing in the universe at that time which designated the planet as Sol System First Satellite Kingdom: Earth. It was one of at least seven satellite kingdoms that were seemingly formed by seraphs and homunculi in a campaign for them to return to paradise. A colony of sorts that seraphs and homunculi lived in was present on prehistorical Earth with no traces left by modern times. Humanoid appearing seraphs were also part of the kingdom and had access to developments such as photons and unrailed elevator technology as their work on constructs such as the Tower of Babel was ongoing.

By the time humans had evolved, respective civilizations rose and fell with time. During the dark ages of Greece it transpired that Sika Madu had remained on Earth and had been experimenting on humans over hundreds of years, where he was accompanied by a young boy named Yu. From his words on increasing their numbers, and their own human based appearances, it is possible seraphs could have had a hand in the spread of humanity. Seeking out Rigr Stafford and Urd Geales, the First had them become vampires. Living as nobles, Krul Tepes and Ashera Tepes were kidnapped and sold into slavery where that institution was practiced then. They too would be transformed into vampires to join Noya Hienma as one.

It was on Earth during the dark ages of Greece that Sika Madu kept the body of his son, Mikaela. In forming a group of disciples consisting of third progenitor vampires to protect the world from a future calamity, Sika Madu was also around demons who some had been turned into. The demons Raimeiki and Byakkomaru, along with Gekkouin and Kiseki-o were active on Earth at this point. Taking Ashera with him, Sika Madu made his way to Japan and influenced events there through human organizations such as the Emperor's Demons. The magics they were involved with would help form the Order of the Imperial Demons to be led by the Hīragi Clan.

Other family house systems would be developed. Where Saito was keeping track of what the First was doing, he would assist some houses form spell craft based organizations of their own, such as the Order of the Imperial Moon led by the Ichinose clan.

Story
By the time Guren Ichinose attends school, there are shikigami that exist on Earth. Magical based assets such as spell tags could be used for various purposes. Where the end of the world was warned about by Saito, various measures were taken by the few organizations that knew about this scenario. It was such organizations that would be left standing in the world after the catastrophe took place anyway. In binding demons to weapons, cursed gear could be formed to allow the surviving humans a chance to not fully fall to vampire subjugation when the entire world essentially fell into their hands.

Where a Horsemen of the Apocalypse was seen to have been formed, it would be this creature that would go on to populate the devastated Earth after the calamity. The Horsemen of the Apocalypse targeted humans, who sought a kind of refuge with vampires. A provide blood for protection arrangement where humans lived as livestock was the fate of many in the new world. It transpired that a contained seraph was behind the generation of Horsemen of the Apocalypse on Earth.

Earth's trajectory would be seismically altered after the Horsemen of the Apocalypse vanished from the world as it allowed humans to venture forth for them to potentially shape its future. Where wars have occurred, it is the Hyakuya Sect led by Saito that appears to be positioned to decide Earth's future more so since he has the support of progenitor council vampires plus has Shikama Doji captured.