Rei Serizawa

Rei Serizawa (芹沢 零, Serizawa Rei) is the main male protagonist of Extermination. He is the host of the Frost Lord Orcus and the first-created Cherub Mikhail.

Appearance
At the start of the series, Rei is a tall, handsome and slim sixteen-year-old with unkempt jet-black hair jutting in all directions and supernatural orange eyes behind a pair of black glasses. Having spent a year in the barrier alongside Chisato and Eros in volume XIV for the Divine Contract, his hair has grown a bit longer, as well as being taller and more muscular. In volume VIII, Rei has been described as having big burly build and arms.

He also has scars that cover most of his body, which is the result of the Shrine Church exploding, however, he just tells people, he was involved in a car accident as a child.

Throughout the series, he is often seen dressed in his school uniform in Kimura Academy even when in combat. However, when outside of school, Rei is dressed in more casual clothes.

After Volume XI, he now has an X-shaped scar across his chest, courtesy of Eliza Serafim and Michella.

In Volume XIV, upon having the power of Orcus and Mikhail and the five elements in a perfect spiritual balance, Rei is able to manifest a full body armor, referred to as Nephalem Cocytus, making him look similar to Masaomi Haruno in his corrupted Wöden form while retaining his humanity.

Personality
Overall, Rei has shown to be laid-back and collected a great number of times, but there are times when he can also lose his composure in either awkward or embarrassing situations most of his time in his daily life, displaying great shock annoyance, and even at times anger.

Due to the incident that occurred in the past, while in the Tatsuyama Village as a child, Rei suffers from frequent nightmares as a result of being forced to kill his Undead friends and comrades and being unable to save his parents from the Shrine Church explosion.

He is also compassionate and is a firm believer in the idea of family, desiring to protect those closest to him no matter the cost even if it puts himself in the most danger, which goes along with his sense of right and wrong. Despite him being a former member of the Tatsuyama Village, Rei still decided to protect the Suzaku Doll after hearing about her difficult past and situation from Hisashi Sumeragi, as well as knowing Aoi hadn't done anything wrong, to begin with. This has even led to him fighting against his former childhood friends to defend her.

Due to the nature of the Belialuin Vow, Rei never desired to have his relationship with Aoi forced and based on that alone, due to him wanting them to become a real family. Both Orcus and Masaomi have described him as being too greedy, desiring to protect everything important to him going to such extreme lengths like making a deal with Vanagandr to watch Uvall's death, as well as killing Rudolph Rubestein, a high-ranking official in the C.P.S., before his match in secret on both occasions. Rei has a habit of restraining himself with the girls during their "conquests", but after his interactions with both Eros and Chisato Hasegawa, he has started to become more and more sadistic.

Despite showing to be calm most of the time, there are moments when he goes into a frenzied state if anyone he cares about could be killed in the process as shown when he thought that Masaomi had killed everyone important to him using Kouryuu and Gonggong. Much like his later father, Rei isn't afraid of going against the Tatsuyama Village, the C.P.S. and even against Gods themselves in order to protect his beloved.

Aside from just his sheer combat skills, Rei has also shown to be calm and analytical using whatever means possible to make a situation go into their favor during political situations, which is mostly shown during the battle against the (C.P.S. governed) Enosichton and Cocytus Factions when he killed Rudolph before his match started, then he also planned to kill the other Council Members during the chaos caused by the arrival of both Aegaeon and the other Daemons. Then during the conflict caused by the Tatsuyama Village who viewed him and the others as too much of a threat, then decided to control the corruption level that the they had with the spirits and gods to his advantage.

History
Rei is the biological son of Hiroyuki Serizawa and Maria Haruno conceived after she and Hisashi Sumeragi rescued Hiroyuki from the Dimensional Domain of the Yahweh-Daemon.

Rei was raised by his parents and later younger brother Takashi Serizawa within the Tatsuyama Village, where he was viewed as a genius from a young age during his training with the other children. However, when he was around the ages of eleven or twelve, his childhood friend, Seito Toujou, was tricked by the Vampyre King Nosferatu into allowing him into the village, and ended up being possessed and went on a rampage killing a number of adults and even Rei's other friends.

TBA.

Powers & Abilities
As a child, Rei was viewed as a prodigy classified as B-Rank despite his age having inherited talent from his father. However, his skills dulled having not trained for five years after being exiled from the Tatsuyama Village, while still stronger compared to a normal human, even without Orcus' power. Though due to his battle rust wearing off and the constant strengthening from Orcus' power, Hisashi stated that he is far stronger compared to five years ago in Volume VII; he was classed as S-Rank after he returned to the Village. Having finished the Belialuin Vow and gaining both the Five Elements and Orcus Cocytus, he was able to hold his own against Masaomi Haruno albeit the latter was still superior to him in Volume XIV. In the Volume XIV Epilogue, his strength rivals the strongest among the Daemon Lords.
 * Enhanced Strength: It was first seen in Volume 1 when Rei easily sliced straight through a rogue Daemon with a sword slash.
 * Immense Durability: Rei is far more durable compared to that of normal humans, being able to survive wounds such as being stabbed in the same spot twice, both times waking up moments later. Due to both his training and strengthening of the Daemon Contract, he could endure attacks from powerful enemies and endured two ki strikes from Masaomi, albeit he would've died if not for Chisato and Mikhail saving him.
 * Immense Speed:
 * Magic Resistance: Rei is unaffected by low-class magic, as revealed in Volume 1.
 * Ki Manipulation:
 * Magical Barrier (魔法の結界, Mahō no Kekkai): As a side effect of the Belialuin Vow, Rei became able to create a powerful magic barrier based around his blood, five elements, and Yin-Yang. He mainly uses this barrier so that he can have outside sex with his harems without them worrying about others seeing them, which the other girls can use as well.
 * Replication: Rei can create up to four clones of himself via Magic.
 * Banyuusekiryoku : As the biological son of Maria Serizawa, the Cambionized host of Taribatum, Rei is able use Maria/Taribatsum's power to control and amplify gravity using the souls of Rudolph Rubestein and Zaqiel.
 * Divine Contract:

Master Swordsman: Rei is a remarkably skilled swordsman, as a child, he was hailed as a genius who could gain the upper hand against even experienced swordsmen. Despite not training since his banishment, he cut Lilith's magic bullet, then held his own against Garo despite already being injured from before, and later was able to cut through Richter Steel's Iron Armor. As Rei continued to face off against powerful enemies, he trained his sword skills with Hisashi using his speed and skill to his advantage against even Richter and held his own against Celis and Hisashi.

Expert Scythe Wielder:

Other Skills
Sexual Dominance Expert:

Deductive Reasoning: Rei has consistently proven that once given a bare minimal amount of evidence he is able to deduce the true identities of many of his enemies and their plans even when they try to hide from him.

Sensory Perception: Rei's power had increased by leaps and bounds by the conclusion of the Underground Arc. Upon returning to the Human World, he became able to sense and feel things he was unable to notice before. This ability gets further developed in Volume XII, as evidenced by Rei being able to sense the Daemon spy based upon their Ki.

Strategist:

Daemon
Orcus (オルカス, Orukasu) is Rei's Daemon, who he met during Orcus' escape from the C.P.S., also known as the Frost Lord (霜魔王, Shimo-Maō). One of the Three Great Daemons of the Underground, Orcus takes the form of an black, slime-like substance around Rei's body with blueish-purple eyes, and give's Rei the ability to manipulate ice on an massive scale and form the slime into weapons and armor for combat and defense.
 * Scythes: After the fight against the C.P.S. in the Underground, Rei learned to create and produce scythes with Orcus's power which he uses as his main weapons for melee combat. In Volume XII, Rei was able to summon a new scythe covered in red flames, which is the result of Mikhail.
 * Cryomancy (Ice Manipulation):
 * Daemonic Armor: During volume IV, Rei used a special medicine Florence Nightingale prepared to stimulate Orcus' original power and Rei's innate 'flame', later revealed to be the Ame-no-Ohabari, making it possible for them to further synchronize with each other even more. As such, he dons a black Demonic battle armor with a blueish-silver armor cover his entire arm, an icy halo-like object on his back; ice appears around his body and mist emits from him; and parts of his hair turns white. This armor boosts his power to the point of being able to overpower Richter Steel and Rafael in battle. However, the Demonic Armor puts a strain on his mind and body, sending him on an uncontrollable rampage.
 * Cocytus Nephalem Dive (, Ice Daemon Lord's High Heaven Armor):

Cherub
Mikhail (ミハイル, Mihairu) is Rei's Cherub who he made an contract with him after Eliza's defeat, also known as the First Cherub (最初の, Saisho no Cherabu) and the Burning One (熾天使, Shitenshi).
 * Swords:
 * Pyromancy (Flame Manipulation):
 * Healing Flames:

Equipment
Ame-no-Ohabari : The legendary Spirit Sword, one of the Totsuka-no-Tsurugi, used by the God Izanagi to slay his son Hi-no-Kagutsuchi after the latter accidentally killed his mother Izanami, being imbued with Kagutsuchi's fire power. The Ame-no-Ohabari chose Rei as a partner in Volume V because of his dedication and loyalty to towards his friends, as well as his burning hatred towards the C.P.S..

At first, he wasn't as compatible with Ame-no-Ohabari due to viewing it as a tool as he still feared it. Though, he overcame this by overcoming his fear and accepting his true nature, dramatically raising his compatibility. In his battle against Eliza Serafim and Michella, Ame-no-Ohabari shined a shining red light causing all the light sources and plants around him to burst into flames, then displayed immense power that outmatched even Daemon Lords and First-Sphere Cherubs.

Táowù : One of the four cursed treasures kept in the Tatsuyama Village, which Rei borrowed in Volume XIII to save Seito, Takehito, Vangeance and Celis and to locate Masaomi who had stolen the other three. He was forced to replace it with Ashkelon, in which was used to manifest a replica Taowu after Loki removed it threatening to destroy the barrier and release the three of evil beasts into the Human World.

Trivia

 * His first name Rei (零) means "Zero", a reference to Absolute zero, the theoretical temperature at which atoms stop moving, referenced by Orcus' ice-based powers.
 * His surname Serizawa (芹沢) means "Parsley Swamp".
 * Growing up one of his favorite meals was Kaoru Nonaka's beef stew.
 * Celis revealed that his or, if Rei didn't take the blame, Seito's banishment from the Tatsuyama Village was a decision of The Elders and not the Vatican or any others, meaning that it was possible for it to be overturned.
 * His first time having vaginal sex was with Aoi.
 * His first time having anal sex was with Mio.
 * His first double penetration sex was with Eros (Rei grew a second penis).
 * Rei has daily threesomes at night since the group decided that two girls would sleep with Rei in their room at the same time. Some of the known duos are:
 * Aoi and Mio
 * Aoi and Yuki
 * Yuki and Kurumi
 * Lilith and Kurumi
 * Aoi and Galatea
 * Eros and Zhu
 * Mio and Lisa
 * Rei is aware of Rikka Kajiura's feelings for him, Rei even has fantasies where he has sex with her but, since she is a normal human girl, If she was to become Rei's sex slave would be dangerous for her, so her chances of joining the harem are very low.
 * According to Exhibition, Rei's strict upbringing as a member of the Tatsuyama Village made it easy for Rei to repress his sexual desires early on in the series.