|Alias||Kaleid Blood, The World's Strongest Vampire, The Fourth Primogenitor|
|Height||176cm ( 5' 9" )|
|Eyes||Aquamarine Blue (Red when blood lust takes over)|
|Occupation||Student (later becomes the leader of the empire of the dawn)|
|Base of Operations||Itogami Island|
|Relatives||Avrora Florestina (Predecessor / Master)
Gajou Akatsuki (Father)
Mimori Akatsuki (Mother)
Nagisa Akatsuki (Sister)
Yukina Himeragi (Wife)
Asagi Aiba (Wife)
Reina Akatsuki (Daughter through Yukina)
Moegi Akatsuki (Daughter through Asagi)
|Anime Debut||Episode 1: Right Arm of the Saint I|
|Manga Debut||Chapter 1|
|Novel Debut||Chapter 1|
|Japanese Voice||Yoshimasa Hosoya
Mutsumi Tamura (Young Kojou)
The Main Protagonist of the story. He is Nagisa Akatsuki's brother and the childhood friend of Yuuma Tokoyogi. He is a normal high school student except for the fact that he is the fourth primogenitor, the world's strongest vampire that should only exist in legends. When a middle-school girl named Yukina Himeragi is sent from the Lion King Organization to observe him and to eliminate him if he seemed dangerous. He cannot seem to remember how or why he became the fourth primogenitor and he'll get an intense headache whenever he tries to remember the event.
Yukina stated that there's no way that an ordinary human could randomly become the fourth primogenitor and Kojou himself couldn't remember any traces of the incident. There is no doubt that he is a powerful person, when he gets aroused through smells or awkward sexual situations, his vampiric urges take over and his eyes turn red. He can stop the urge by taking some of his own blood whenever he gets a nosebleed. His nosebleed constitution seems to be inherited from his mother, Mimori Akatsuki who has an easy blood flow. Koujo is revealed to be immortal, even by vampiric standards after regenerating from complete decapitation by Rudolf Eustach.
Kojou is a young man with silver-blue hair and blue eyes. His eyes, however, turn red when he is either aroused or angered such as when he sees Yukina cut by Eustach. He is usually seen wearing the Ayami Academy school uniform which consists of a white button up shirt and black jeans. He also wears a blue undershirt and a white hoodie which he wears up both day and night.
Though often clueless to the point of insensitivity, Kojou is a kind person and goes out of his way to help others which is shown when he puts himself in the way of Eustach's axe to sacrifice himself and save Yukina. He is also very laid back and carefree but when his friends are in danger he becomes quite fearsome. He is seen to care and worry for his sister the most.
Kojou was a normal human until he first met Avrora the 12th Kaleid Blood and became her blood servant, a pseudo vampire. Since then, he spent his daily life with her but those days didn't last long until she ordered him to destroy her and became the fourth primogenitor. In addition, he lost his memories regarding the incident and the days they spent together. However, he later regained some portions of it after fighting Giada, the third primogenitor disguised as Avrora using the No.14 Grimoire in attempt to recover his lost memories. He fully regained his memories alongside Asagi after Yukina performed a ritual on them.
He first met Yuuma when he was trying to retrieve Nagisa's hat which was stuck on a branch at the end of a cliff. He looked for Yuuma at her regular spot where she used to hide and watch both siblings everyday and asked for her help. Without waiting for a respond he quickly grabbed her hand and got back the hat together. However, after they did so Kojou nearly fell off the cliff only to be saved by her, he later thanked her and said that she's pretty strong. A while after everyone introduced themselves. He first met Motoki and Asagi during middle school.
He first met Avrora at Fairy's Coffin. Kojou used his body to protect his sister and Avrora from the terrorist attack leaving him on the verge of death. Avrora admired his courage and turned Kojou into her blood servant. Avrora ordered him to destroy her alongside "Root" and chose him as their (the 12 Kaleid Bloods) successor.
Enhanced Vampiric Abilities: As a vampire, he possesses supernatural strength, speed, reflexes and durability. In addition, due to being the Fourth Primogenitor, he has incredible power far above that of most vampires and is virtually immortal.
Familiar Summoning: Kojou has twelve familiars which is a manifestation of his vampire's powers. Initially, these familiars would not fully obey Kojou and would often go on rampage. This is due to the fact that he refuses to drink human blood and thus, they would not acknowledge him as their master. However, he is able to control his familiars and summon them properly once he drinks blood. It is revealed that Kojou is still lacking three familiars inside him, one of them is the 12th that lies inside Nagisa while the 6th and 10th still have their Kaleid Blood bodies. They are currently in Oceanus Grave II under the custody of Vatler. Everytime Kojou releases new familiar, he says the following chant:
I, Akatsuki Kojou, successor to the blood of "Kaleid Blood", now release your constraints. Come ....(number and name of familiar)
"カレイドブラッド"の血脈を継ぎし者暁古城が汝の枷を解き放つ疾く在れ ...(number and name of familiar)
"Kareidoburaddo" no ketsumyaku o tsugishi mono, Akatsuki Kojō ga, nanji no kase o tokihanatsu. kyagare ... (number and name of familiar)
Brote - Mesarthim-Adamas / The Adamant of God's Sheep
|The medium for this familiar is Kanon. It is a sheep with more than ten thousand diamonds covering it's entire body. This familiar is capable to manipulate diamonds. It is able to spread or scatter them like shotguns and form shields reflecting various attacks/abilities making it well balanced on offense and defense. The diamonds are strong enough to block Al-Meissa-Mercury's dimension eating capabilities.|
Defteros - ? / ?
|? ? ?|
Tritos - Al-Meissa-Mercury / The Serpent Dragon of Mercury
|This is the third familiar shown in the series. Kojou took control of it after drinking both Yukina's and La Folia's blood. It is a double-headed serpent dragon that is also called the Dimension Eater. This familiar is capable of reality warping / eating void and space. It is able to withstand angelic powers. It's mouth can devour anything that acts like a black hole.|
Tetartos - Natra-Cinereus / The Carapace of Silver Mist
|The medium for this familiar is Sayaka and Yuuma. It is a silver crayfish with blue flames on it's claws. This familiar is capable to render anything ethereal by producing mists. Due to the fourth primogenitor's strength, the mists are able to cover the whole island without any difficulties. In episode 19, it is said that this familiar was only half-materialized as a wound on Kojou's chest (when Himeragi stabbed Kojou). The mists are strong enough to ward off reality warping.|
Pemptos - Regulus-Aurum/ The Golden of Lion
|This is the first familiar shown in the series and is commonly used by Kojou. Kojou took control of it after he drank Yukina's blood. It is a lion-like familiar having glowing red eyes and has a lightning-like mane. This familiar is capable to produce and manipulate lightning. Kojou is able to manipulate the lightning to create a force field around him. The lightning is strong enough to weaken a divine vibration barrier. It can obliterate several hundreds of kilometers by just releasing it's powers.|
Ektos - ? / The Amber of Minotaur
|It is a minotaur armed with an axe that controls land.
One of the three familiars Kojou does not yet possess.
Evdomos - Kiffa-Ahtel / The Black Sword of Abraded Night
|The medium for this familiar is Yukina and Sayaka. It is an intelligent-type weapon, a gigantic demon sword over 100 meters in length. This trident-like sword is capable to manipulate gravity. It can obliterate few dozens of kilometers if swung from a high altitude.|
Ogdoos - ? / The Flame of Manticore
|It is a manticore that controls fire.|
Enatos - Al-Nasl-Minium / The Crimson of Bicorn
|This is the second familiar shown in the series. Kojou took control of it after he drank Sayaka's blood. It is a bicorn-like familiar having glowing purple eyes, black-colored skin, purple fire-like mane and has glowing plate-shaped armor floating around its neck. This familiar is capable to produce and manipulate sound. It is able to create sound quake and waves. It can tear molecules at an atomic scale by emitting high-frequency vibrations from it's entire body.|
Dekatos - ? / ?
|? ? ? / One of the three familiars Kojou does not yet possess.|
Endekatos - Sadalmelik-Albus / The Water Spirit of White Steel
|Avrora awakened this familiar by force while in Nagisa's body and subsided by , then gained control of it after drinking Yukina's blood.'s blood. It is a combination of an undine and a snake. This familiar is capable to revert phenomenon to it's original state which is nothingness. Due to this ability, Kojou is able to recover from any kind of injury including decapitation as shown in the series. It is able to to erase conceptual existence.|
Dodekatos / Avrora - Alrescha-Glacies / The Demon Princess of Blue Ice
|It is a combination of a siren and a mermaid. This familiar is capable to decrease temperature below absolute zero to which was first seen with his sister Nagisa, who has a part of Avrora currently living inside her.
One of the three familiars Kojou does not yet possess.