Sanguinem

Sanguinem (サングィネム) exists in the world of Seraph of the End and is the third capital and third largest city of the vampire world. Located underneath the ruined city of Kyoto, it is home to prominent vampire nobles, such as Ferid Bathory and Krul Tepes.

Details
In the manga, Sanguinem is a large city beneath Kyoto. It is extravagant with buildings in 18th-century design, churches and cathedrals, and elaborate archways. There are also European-style houses. The ground often consists of either tiles or stones. The city is set at one level, but many buildings have multiple stories. There are numerous large pipelines throughout the city.

Krul Tepes lives here in a large, elaborate mansion with a massive entrance hall. Her throne sits in the back center of the hall, and the hall is empty and without stairs. There are many elaborate arches on either side with detailed panels decorating them. There are also books, which humans are free to read. One is Notes on Nightwalkers, which Yūichirō Hyakuya reads in chapter 1. Mikaela Hyakuya may sometimes be found sitting silently in the pews of one of the cathedrals all by himself. The homes of livestock are plain with tiled floors, blank walls, and no furniture.
 * Anime: Sanguinem is an elaborate and large city composed of several bridges and waterways. There are many levels to the city. The buildings are designed in an 18th-century style, although some modern structures also exist. The churches and cathedrals are not shown, and the large pipes do not decorate the buildings. Krul's entrance hall has stairs and a long rug. The humans have furniture, and they wear shoes. Additionally, the house the Hyakuya orphans use is made of wood and has a loft. They have furniture, and there are many papers decorating the walls.

Society
As the capital, Sanguinem is a center of politics in the vampire world. Important issues are discussed in the city, and it may serve as a meeting place for powerful nobles. It is not surprising that numerous vampires reside in this large city. Ferid Bathory lives in the city in his mansion, whilst Krul resides there as vampire Queen of Japan. Humans also live in the city, serving as livestocks for the vampires. Most of these humans are children, and many were brought here during the Apocalypse in 2012 like the children from the Hyakuya Orphanage. Some of these children were sent by Kureto Hīragi to act as his spies and gather information from the nobles. The vampires are not allowed to drink human blood directly from the livestock within the city. In the manga, the vampires remind the humans that they live at the mercy of the vampires, but they aren't violent toward them except during rare instances, such as when Ferid Bathory killed the Hyakuya orphans. The livestock are raised to believe the world above ground has been destroyed, so they have no reason to escape. Unlike in the vampire cities above ground, the livestock cannot come and go freely as long as they do not know the locations of the exits.
 * Anime: In the anime, the vampires are regularly violent toward the livestock, going so far as to even step on children drawing in the street and dangling Yūichirō Hyakuya off the edge of a bridge when he misbehaves.

Known residents

 * Ferid Bathory
 * Krul Tepes
 * Lacus Welt
 * René Simm
 * Yūichirō Hyakuya (Escaped)
 * Mikaela Hyakuya (Former resident)
 * Akane Hyakuya (Deceased)
 * Kōta Hyakuya (Deceased)
 * Chihiro Hyakuya (Deceased)
 * Ako Hyakuya (Deceased)
 * Fumie Hyakuya (Deceased)
 * Taichi Hyakuya (Deceased)

Prologue
Yūichirō, Mikaela, Akane, and other children that survived the Apocalypse on Christmas of 2012 were deported to Sanguinem from Tokyo to become livestock for the vampires. Krul specifically collected the children from the Hyakuya Orphanage because she wanted the surviving seraphs.

Prologue
Four years later, Mika stole a map and gun from Ferid Bathory, and he attempted to escape with his family of orphans. Ferid waited at the exit for them, slaughtered most of them, and dismembered Mika. Only Yu escaped into the outside world after he was able to shoot Ferid in the head. In order to save Mika's life, Krul turned Mika into a vampire in order to save his life.

Shinjuku Arc
The vampires in Sanguinem discuss the growing threat of the Japanese Imperial Demon Army. Krul declared war on the JIDA for the crimes of killing their kin, stealing their territory, and dabbling with taboo magic.

Post-Nagoya Arc
Three months after Nagoya, Kureto and Guren lead their army into Sanguinem and wreck the place. Mirai appears with them in her Seraph form.

However, due to Krul Tepes and Ferid Bathory's failure to repel Kureto and Guren's attack, Second Progenitor Urd Geales and Third Progenitor Lest Karr had personally traveled to Japan together with a large contingent of vampire nobility to retake the fallen stronghold. After punishing both Krul and Ferid, and learning of former Second Progenitor Rigr Stafford's presence in the country. Urd and Lest proceeded to lead an attack to retake Sanguinem. The Vampire force successfully routed the JIDA, removing the enemy forces from their capitol city and reclaiming the stronghold for the vampires once more.

After Ky Luc had returned with former Queen Krul Tepes after retreating from the combined forces of the Rogue JIDA soldiers and former seventh and thirteenth Progenitors Ferid Bathory and Crowley Eusford, Ky proceeded to escort her to one of the city's prison cells to be interrogated by Lest Karr and Urd, where he then amusingly watched the interrogation and proceeded to learn of Krul's true motivation for her actions together with his superiors.

The exit hall of Sanguinem is viewed by Demon Mika when he accesses Yu's deepest trauma. Standing near some columns, Demon Mika observes the scenario of Yu with Mika as children after their orphanage family had been murdered by Ferid. This location and what transpired here were the first indication that Demon Mika did in fact know Yu. The exit tunnel to the outside world was seen. Sanguinem and the event associated with it form the deepest wound in Yu and Demon Mika's hearts. Within the memory of it was where Yu and Demon Mika vowed to save one another, before fighting which resulted in Yu being decapitated.

When Mika has regained his memories and is himself as a demon, two scenarios involving Sanguinem are seen in memories he accesses. Viewing the moment of Ferid about to be shot, it is felt he allowed Yu to escape the city. Observing his own memory, Mika sees Krul before she transfers her blood. This incident is either viewed by Mahiru-no-Yo who may have been invisible there at the time, or by Mahiru Hīragi who was presently watching, having entered the memory Mika was accessing.

It is remembered how as children Mika pushed Yu for him to escape. The interior of the city is envisioned when Yu is detailing to Mika that they are still trapped and helpless just like the were when the vampires had them. The exit hall is present in the imagined scenario of Yu and Mika with their orphanage family departing the city.

Trivia

 * "Sanguinem" means "Blood" in Latin.