Yūichirō Hyakuya

Yūichirō Hyakuya 「百夜 優一郎, Hyakuya Yūichirō」 is a member of Japanese Imperial Demon Army's Moon Demon Squad and is the main protagonist of the Owari no Seraph series.

Appearance
Yūichirō has medium length black hair which can be considered quite messy. He possesses sharp green eyes which fall under his thick eyebrows, His eyes are large compared to most other male characters in the series. He is usually shown wearing a typical Japanese school uniform with a white sleeved T-shirt beneath.

After joining the Imperial Demon Army, he takes on their uniform consisting of a black jacket with light green details, and dark gray trousers and black boots which go underneath his trouser leggings. Yūichirō keeps his sheath on the left side of his hip. Sometimes he can be seen wearing the Japanese Imperial Demon Army hat.

Personality
He is brave, fearless and somewhat reckless, as evidenced when he defeated one of the four Horsemen of the Apocalypse while ignoring orders which is noted not to be the first time. He is a very narrow minded person, whose goal is to annihilate all of the vampires because of what they did to his "family"; overcoming any type of challenge in order to accomplish it.

Despite this, he has a soft spot and worries about his friends first and his goals second. Some (mostly Vampires) consider his personality as 'cute' like Felid Bathory. Also he empathizes with others who put their family first, as seen when a civilian girl gave them false information because she was threatened by a vampire that they would kill her parents. After finding out about this, he told the girl that she did the right thing to save her family. After recovering from his coma, Yūichirō has grown more mature, as quoted from Shinoa. And after he overcame his worst nightmare, he became more defiant, still having the naivety trait when trying to befriend his demon weapon, Ashuramaru.

It is later revealed that his goal, rather than revenge, is to protect his new friends and family, in order to avoid a repeat of past events.

History
In 2012, Yūichirō's father tried to kill him and his mother kept raving about how he was a demon spawn. Then she lost her mind and killed herself which lead to him being sent to the Hyakuya Orphanage on Christmas day. There he was introduced to  Mikaela and the other orphans. Seeing as the two 8 year olds were the eldest,  Mikaela wanted them to be friends. However, Yūichirō was very distant towards him. Mikaela made it very clear he was the leader, so he punched Yūichirō. Afterwards, he told Yūichirō that he used to be alone like him, but now he had a big family. And from that then on, he had one too. Yūichirō proceded to tell Mikaela of the circumstances that lead to his being there. Then Mika told him with a smile that he was abused by his parents, and then he was dropped out of a car and taken in by the orphanage. The other children then told him their stories. Mikaela then told Yūichirō that they weren't lonely because that day was the day their brother Yuu joined them. During the meeting the director suddenly began to bleed from her nose and mouth, and fell to the ground.

Then while outside they saw as the city was engulfed in flames. They had been attacked by the vampires lead by Kururu Tepes. For the next four years, they lived their lives as livestock for the vampires.

After Mikaela gained possession of a map of the underground, both of them decided to escape the place with the rest of the children from the orphanage.However it is revealed that Felid Bathory, one the Seven Founders, knew of this and killed the other children except for him. After reaching the outside world, he is found by Glen Ichinose, a captain of the Japanese Imperial Demon Army. In order to take revenge for his family, he decides to join the Japanese Imperial Demon Army to gain the power he needs.

Sometime after escaping, he was experimented on and was created into a being that is not human by Glen and the Army.

Story
Four years later, Yūichirō became a private of the Japanese Imperial Demon Army. He still attended school as it was essential in life. And when he was told  'to make a friend', Yūichirō struggled as he considered that he didn't need any and that he hasn't made friends before. He meets Shinoa Hīragi who is assigned as his supervisor and is told if he doesn't cooperate, she will report it to the army and his punishment will be extended. Yūichirō thinks what is even doing here. He starts to remember what he told by the vampires 4 years earlier that the world has fallen into ruin. Glen Ichinose tells him "Rebirth is coming". He accepts Glen's offer to join the army. Yūichirō tells Shinoa what's with her and they've only met. Yūichirō tells her not to stick her nose in other people's affairs. He says he will become strong enough to defeat Glen. He reads the message from Glen, given by Shinoa. He gets pissed at Glen. He says that everyone is making fun of him. He steps in to save Yoichi Saotome from bullies, but is told by Shinoa if he harms any civilians, then his punishment will be extended. Yūichirō is shocked to hear Yamanaka is offered to join Moon Demon Squad yet he doesn't. He hits Yoichi in the head and says he would have gotten himself killed. He tells him to forget the army and that his sister wouldn't want him to avenge her death. He hears the emergency warning. He goes to kill the vampire himself saying Glen will see what he is capable of. He takes out his katana from his locker and wears a angry face. He steps in the class and tells the vampire girl that he is going to kill her. He tells Yamanaka to take the "girl" away. Yūichirō says that he has been chosen in the army. He is shocked to hear Yamanaka lying about being joined in the army. He says he doesn't his help. Yūichirō attacks the vampire girl using his katana. Yūichirō shoots her with a gun, but it didn't hit. Yūichirō cuts the vampire girl's arm who grabbed his neck by the other hand. She kicks out of the window. His sword stabs into her chest, but Glen appears and kills her himself. Yūichirō tells he shouldn't have interfered. Glen compliments him. Yūichirō tells him to let him join Moon Demon Squad. Yūichirō gets mad and says he doesn't need friends to kill vampires. He is suddenly hugged by Yoichi who is in tears. Yūichirō starts remembering his past again. When he opens his eyes, he's crying and reaching out his hand. Yoichi and Shinoa become his partners from today on. Blushing Yūichirō says he is looking forward to work with them.

Natural Abilities
Yūichirō seems to be a excellent swordsman, as he was trained by Glen himself. This is shown when he killed a Horseman of the Apocalypse using only a sword.

Demon Weapon

 * Ashuramaru 「阿修羅丸」: Ashuramaru is a demon of the Black Demon series. It resides inside a black sword that Yūichirō uses. Whilst in use, the blade develops a thick green aura. Like Shinoa Hīragi, he can call upon Ashuramaru to fully use its power to attack opponents. His type is possession.

Trivia

 * It has been confirmed that he has part of him that is inhuman.
 * Since he lived in a vampire city for 4 years, he was able to learn to read and write in English.
 * Yūichirō means "Superior First Son".
 * Hyakuya means "Hundred Nights".

Quotes

 * 'If Mich needs me... If Glen, Shinoa, Yoichi and Kimizuki need me, I don't care if I'm a devil or anything.' - Yūichirō to Ashuramaru in The Demon's Nightmare.