Vampire Prison

This vampire prison is a facility in Seraph of the End that was capable of restraining vampire nobles. It was used by Urd to keep Saitō imprisoned after he was captured. When the First was seized, he was also confined within.

Background
After Saitō was found by Urd and other members of the progenitor council including Lest Karr and Ky Luc he was confined to this prison. Lest Karr confirmed that Urd made the prison and speculated that it was designed to specifically hold Saitō. It had taken centuries to create, and could be formed outside with no particular location apparently being a requirement. Restraints included those including a throne like chair with wrist bindings. A chain could also strap a prisoner's hands near the ceiling. A magical based contraption as well, Spell Circles were a feature of the prison, and apparently also large cross like utensils spread around outside of it.

In terms of capabilities, this prison was not only able to prevent a vampire from moving, it was also able to adapt its strength to that of its prisoner. The older the vampire the more tightly the prison's chains would bind them. This also applied to Shikama Doji, one of the strongest beings in the world. As from the outside, individuals could place their limbs and weapons through the bars, there may not have been any means of preventing someone from breaking a prisoner out. For all the restrictions on the prisoner inside, it did not stop Shikama Doji from being able to telepathically communicate with vampires on the outside, a brainwashing spell that also appeared to physically harm them.

Appearance
A cube shaped cage had vertical bars making up the walls, where the ceiling and floor were both flat. Within this cage was situated what appeared to be a carved stone throne like chair. The armrests had iron appearing wrist restraints which were the only apparent physical means of keeping a prisoner seated. Physical imprisonment was supplemented by prisoners being bound by chains wrapped round their upper body to the backrest of the throne multiple times.

The floor this chair was placed on was identical in appearance to the ceiling of the cage, with lines similar to planks of wood visible. The throne was in the middle of what resembled a shining spell circle on the floor with an inner border able to be distinguished. This visually predominant circle had other smaller ringed circles overlapping it in different places. There were two double circled rings and two single lined rings, where all five designs were connected and were of varied sizes.

Around this contrivance were many large cross like implements of differing heights which seemed dependent on how deeply sunk into the ground they were. Some of them were much taller than the cage. These crosses were spread in the near area seemingly randomly, and were positioned at an angle.

Story
After the battle of Shibuya where Saitō led the Hyakuya Sect in an invasion of the city to restrain the first, he experienced a defeat that Ferid and Crowley had a hand in, and was consequently apprehended then incarcerated by progenitor council members who were also present. Saitō sat humming to himself in this prison with Lest Karr, Ky Luc and other vampires standing watch. While the combined physical and magical qualities of the prison were on the surface achieving their purpose of preventing Saitō from moving, the ends of the armrests were crushed after he gripped them suddenly. When Saitō entertains the idea of killing everyone present, Lest Karr informs him he cannot since the older the vampire the more tightly that prisons's chains bind them. Saitō professed he could not move an inch and found it incredible, before expressing surprise that something like this could be made. After Lest Karr states it was probably made to contain Saitō, and took centuries to make he answers that Urd was the one who made it. Within this prison is where the time Saitō defeated Urd in Romania is recalled.

With the possibility of Saitō being executed he attempted to induce Lest Karr into freeing him, and Ky Luc commented on whether they should open it up, indicating that there was a method to unlock the prison from the outside. When the attempt to sway Lest Karr with secrets on why the First had other third progenitors join his cause but not him failed, Saitō resorted to physically breaking out himself. This was done when Saitō's chains ruptured out the back of the throne, and the ceiling of the cage was ripped asunder with Saitō able to raise himself into the air on his chains where the prison was unable to prevent this.

The escape revealed as an illusion, the prison was unbroken and intact, yet had been opened through some means when Saito was released. It remains fully formed when Saito is generating a pentagram of chains and is referred to when he mentions a jail that drains the more power the older the vampire it holds. Having the referred to target in there, the prison is used to keep Sika Madu confined after he was seized by chains. A chain binding around the First's wrists keep him upright, instead of a throne.

Kept in the prison, Shikama Doji speaks with Saito on the eternal life they have. Where Saito is able to reach through the bars from the outside to grasp Shikama Doji by the throat, his chains can also enter though the prison as well. The prison floor has Shikama Doji's blue blood drip onto it from the wound Saito inflicted.

From his confinement in the prison, Shikama Doji is able to also speak telepathically to communicate with the vampires outside. It is within this prison that Shikama Doji reveals that the price of resurrection is seven sinful keys, and the lives of every last vampire.

The cage itself and spikes nailing Shikama Doji appear all that is now required to contain him. The prison has been transported and placed within a building of Shibuya. This is affected by the light radiating from defensive sigils established by Basteya Irclu along with members of the Hyakuya Sect.

While Shikama Doji is awake, the prison plays a central part in seemingly allowing the First's memories to be accessed by Saito to learn details of his past. Cables have been attached to the First's head as he remains confined. With the stakes ever-pinning him to the floor, Shikama Doji is kept confined for Saito to place his finger in his head while Urd observes from outside the bars.

Due to the prison's confinement, memories of Sika Madu having a homunculus bring the first humans seen on Earth for angel spirits to fly into them, which included human appearing angels, is able to be observed by Saito. That there appeared no means of escape may have allowed for the time for Saito to view memories of Trumpets of the Apocalypse along with a human appearing angel destroying the Seraph Civilization that was present on Earth during its prehistory at God's direction.

What the prison's capabilities certainly allowed for Saito to witness was the link between humans and angels, which would tie into vampires that would come into existence in later ages. This may have included a human link between Bael and Urd and a human link between Paimon and himself. From the memories accessed here, Saito would reverse from wanting to obstruct the First's goals by any means, to sympathizing with what he has endured for them for so long.

The prison may have allowed for Saito to observe that Mikaela's spirit had entered the body of a child who then had the homunculus named Yu assume his body. It is unclear if Saito saw this and so learn that Sika Madu could never resurrect his son as the corpse he had was the homunculus imitating Mikaela's physical body, where Mikaela's spirit was actually hidden inside a human.

Quotes
"True. I can't move an inch. This is incredible. I'm surprised you could make something like this."

- Being impressed with the prison containing him may be genuine, yet by resorting to his chains Saitō would easily break out.

"It was probably designed specifically to hold you. It took centuries to create."

- Lest Karr speculates why it was made (for Saitō) and is aware how long it took to make.

"Why'd you create that cell, by the way? A jail that drains more power the older the vampire it holds. Who do you think really belongs in there?"

- Freed from the cage he was in, Saito has questions for Urd. The 'who' in context likely is a reference to the First.