Yuuki Anzai


 * This article contains major plot spoilers from the manga that have not been revealed in the anime. Proceed at your own risk.

Yuuki Anzai (安斎 結貴) is the male protagonist of the Devils' Line series. He is a a half-devil, half-human police officer who was part of the F Squad in the MPD Public Safety Division 5, who is responsible to combat devil crimes as well as arresting devils. His occupation as a police officer utilizes his abilities as a hybrid.

He is a part of the 15th Hybrid Birth Project at ONLO in Hokkaido, where he was born and raised.

Although he isn't a pure-blood devil, he still yearns for blood like any other devil but has a strict rule of not drinking blood. He has always despised the devil inside of him and devils in general, and he was also pessimistic regarding the coexistence of devils and humans. However, his thinking has been changing since he met Tsukasa Taira, who became his girlfriend throughout the series.

History
Yuuki Anzai is a hybrid, and the only child born to a devil father, Tamaki Anzai, and a human mother, Midori Anzai, for the purpose of being made to be a part of the Red Group of the 15th Hybrid Birth Project at ONLO in Hokkaido. These devils are called "Children of/(raised under the) Light" by some. Since sexual intercourse with humans and devils are very hard, Yuuki was conceived with artificial insemination; with Midori's eggs and Tamaki's sperm. Also, due to Yuuki's mother being a very talented researcher, they couldn't afford to lose her since being pregnant with children with devil blood could cause problems. Yuuki was therefore carried by a surrogate named Ibuki Takeya.

However, unlike Johannes Kleiman, he was excluded from the hybrid experiment due to being physically weak, bad with blood and wasn't experimented on at all. He was thus placed in the orphanage in ONLO along with other devil orphans, but he still had to be monitored. This is the reason why Yuuki never got a parent-child relationship with his parents. However, his mother (who was working at the orphanage) looked over him, though Yuuki believed he didn't have any parents. At that time, Yuuki also became great friends with Tadaya Hiruta and Yuuko Tamaru, and the three would often play together. Since he was unaware of having a real family and grew up without one, Yuuki stated that the kids in his ONLO class became his family.

One day, Yuuki was alone and stuck in a tree, unable to get down, and on that moment, he was spotted by Kirio Kikuhara. When Kikuhara got him down, he embraced Yuuki and explained that he just wanted someone like him to become his comrade, and proceeded to ask the little Yuuki to be his friend and follow him, and the boy agreed. However, Kikuhara took him to the basement where there were full of transformed devils, and told him about his serial killer father. He told Yuuki that all the devils were the same as him, horrifying Yuuki. He then led Yuuki to his father and meanwhile told him about his own past and how he killed his mother, this being the same path as Tamaki, Yuuki's father, took. This revelation deeply shocked Yuuki as he simultaneously cried and threw up. Although this event scarred him and being the reason for his resentment of devils, he forgot most of this until he grew up.

When Yuuki was in ONLO High School, he had already thought about becoming a police officer with his best friend, Tadaya, as he wanted to be on the frontline protecting people from the danger of devils. So when he graduated from high school, he was assigned to the F Squad in the Public Safety Division in Tokyo.

Appearance
Yuuki is a young man with a fit and muscular build who stands at an average height,. He has short, messy, black hair, and his most iconic feature is a longer piece of hair that falls down in front of his face. He gets a haircut in Line 42, but maintains this feature. A small beauty mark sits on the left side of his upper lip. Yuuki inherited his mother's black messy hair, smile and beauty-mark, but aside from that, he is noted to look exactly like his father. And since he is a devil who doesn't drink blood, he has prominent dark circles under his eyes.

He often wears a black shirt, light pants, and dress shoes. He is always seen wearing a silver ring with a black cross on his right middle finger. This ring is actually a device for monitoring his body temperature.

Transformed
Yuuki's transformation into a devil usually follows a pattern. First, his eyes will start to turn red. Once they are completely red, his irises yellow and become cat-like. Veins will appear around his eyes. Then, simultaneously, his teeth will sharpen into fangs and his nails into claws. As a devil, Yuuki is stronger, faster, and has better reaction time. Depending on what prompts his transformation, it can happen slowly or nearly instantaneously. Feelings of passion usually mean a slow transformation, when confronted with blood it’s faster, and in life or death situations it’s even faster.

Personality
At first, Yuuki seemed to be a withdrawn man shrouded in mystery. However, he has a strong sense of justice and can be confronting and sensitive regarding devil-related crimes and matters. He acknowledges the devils' influence in society, which is why he became a police officer - to protect people from the threat of devils. He is generally calm and collected but can turn very violent and dangerous, especially when it comes to protecting Tsukasa. He cares deeply for Tsukasa and his comrades, and will rush to their side whenever they are in trouble. This is seen when he transformed instantly after Tsukasa got shot. He let out a cry even while in his transformed state when he found out that she wasn't injured. He is warm and friendly towards those he cares about, and although he doesn't smile so often, he will smile and laugh and is happy around close friends like Tadaya, and also particularly Tsukasa, and will sometimes freely show his enjoyment towards various matters. But around his enemies and people he doesn't like, Yuuki will turn cold and blunt, and doesn't care whatever happens to them.

He is mature and responsible, but can at times act without considering the consequences of his actions in which he lets his emotions take the better of him. According to Johannes Kleiman (Hans Lee), Yuuki is easily manipulated emotionally and although he looks and acts tough, he is actually a "crybaby". As noted by Lee, instead of finding a resolution or talk about a problem (as in Yuuki's relationship with Tsukasa), Yuuki thinks it would be better if he distanced himself from Tsukasa a bit. He doesn't like holding grudges towards other people when it involves his own matters, and when he is at fault, Yuuki will push away his pride and apologize properly. But when it comes to Tsukasa, especially, he holds grudges and resentment towards people who have caused her harm in any way (if they are not genuinely sorry for what they did).

Yuuki is very self-deprecating, he despises the devil inside of him which causes him to have thoughts he doesn't want to have. He thinks he's filthy and creepy when in his transformed state, and not because someone said so, but because he himself thinks so. This is why he is rather shocked by the way Tsukasa is so accepting of him, and is reluctant to spend time with her in the beginning. He was also rather pessimistic towards devils and humans coexistence, but after meeting Tsukasa, his thinking regarding this matter has changed. They are always trying to make their relationship work, in their own way, but Yuuki is still self-conscious. But although he still isn't fully accepting of himself, Tsukasa has helped Yuuki is a lot of positive ways and gave him boost in his self-confidence. And exactly because of how dear Tsukasa is to him, he decided to break up with her for a while to sort out of his feelings and clear his confusion, and then see her again. He just doesn't want to put Tsukasa in dangerous situations and make her worry. Although they had separated, they are now together again and states that will always stick by each others side no matter what.

In Tsukasa's presence and when she says something sweet to him or displays jealous behavior, Yuuki turns very flustered and embarrassed. She is the only person Yuuki shows this side to. It is mentioned that the majority of the times Yuuki has transformed is when he's lusting for Tsukasa or when it revolves around her. Sometimes, his lusting for Tsukasa resulted in some private perverted acts, such as in one time when the thought of Tsukasa strongly urged him to masturbate, while lustfully staring at a photo of Tsukasa on his phone. He would later feel embarrassed by the act, but only a few minutes later after cumming, he would be lustful again and play with himself again a second time.

He also has some comical sides to him as well, and can at times be scolding, short-tempered and have arguments with Lee who is the complete opposite of him.

Tsukasa Taira
Yuuki was initially very hesitant to spend time with Tsukasa due to his thinking that humans and devils shouldn't live together. However, after their first encounter, he kisses her upon seeing her blood. Although he planned to never see her again, he was worried how she was after the incident with Shouta Akimura. He then regularly started to visit her and quickly fell in love with her. He was very shocked at how accepting she was with him and began seeing her as a person he had to protect. Yuuki grew very protective of Tsukasa and cares for her well-being more than anything. He also tends to become jealous when other guys swoon over her, but doesn't push it. After they become an official couple, they are seen to be a very a straightforward, loving, trusting and dedicated couple. At the same time, Yuuki is very scared of hurting Tsukasa or coming off as indecent, in which he troubles himself to stay away for the fear of hurting her. He loves her so much that he doesn't care what happens to himself as long as she is safe. He sees her as his family, and the place he wants to go home to every day. However, his mixed and draining thoughts about the coexistence of devils and human, made him break up with her for the time being so he could sort out his feelings and face Tsukasa straight-on. After going back together, they are stronger than ever and does everything to be able to live together.

Trivia

 * His average sleeping time is 6 hours.
 * His favorite foods are milk and chocolate.
 * He prefers having slip-on shoes.
 * Yuuki has had a class 1 driver's license since 2010, which means he got it when he was about 18 years old.