|“||The only work I hate... is that of a Butei.||”|
|“||--I'm a senior high school student. My grades are slightly below average, and I attend a violent school.||”|
–Kinji Tohyama, Volume 14, Chapter 1
Kinji Tohyama (遠山 キンジ Tohyama Kinji?) is the main male protagonist of the Hidan no Aria series. He is a Rank-E Inquesta student at Tokyo Butei High School. Formerly, he was an S-Rank of the Assault department, however the death of his brother caused Kinji to seek quitting the life of a Butei and become a normal person. Despite this, he attracts the attention of the transfer student and Assault Ace, Aria H. Kanzaki, and becomes her partner to clear the name of her wrongfully imprisoned mother.
After enduring many battles throughout the series, Kinji is given the name Enable, the man who can make the impossible, possible. He was also able to bring down the IU, end the Far Eastern Warfare (FEW) conflict, defeated the Scarlet Goddess, which eventually freed Aria's mother.
Kinji later became President of his own militant company, Tohyama Warrior Office after retiring from the Butei in order to keep his Butei license until he stepped down and prepared for college entrance exams
Kinji is a young man of average height and built with wavy black hair and brown eyes. He has been described by others as both handsome and gloomy. Throughout most of the series, he wears his Butei High School uniform. After he retired from being a Butei, he began to wearing a black three piece suit and tie.
Due to the apparent death of his older brother, Kinichi, as well as the ridicule he suffered afterwards, Kinji is a very bitter, cynical and sarcastic young man who rarely has a good word to say about anybody. Before meeting Aria, he wanted nothing more than to quit his life as a Butei and live a normal life, believing his life doesn't have to be special just because he comes from a famous family. However, Aria accuses him of simply running away and being scared of his true potential, and he eventually agrees to become her partner, albeit reluctantly. Kinji has also shown an inferiority complex throughout the series, believing he is unworthy to be the partner of a "winner" like Aria, something that doesn't go away even after embracing Butei life. He almost never smiles, and when he does it's usually his way of acting like nothing suspicious is going on, and therefore hardly ever sincere.
On the outside, Kinji appears to be highly anti-social to most people and especially cold to women, even borderline misogynistic due to trauma with girls during middle school, where he was taken advantage of and being ganged up when trying to stand up for himself. To his classmates, he's often thought as a loser, shut-in, womanizer, and a waste of talent because of his indifferent attitude to the point of feeling isolated among the student body. He's even believed to be homosexual since he shows little to no interest in women.
While under the influence of Hysteria Savant Syndrome, Kinji's personality undergoes a very drastic change. He becomes very smug and smooth-talking, and feels compelled to protect the girl in front of him no matter what, with seemingly no regard for his own life. His personality while in this state is overpowering, to the point that it has caused women to become seduced and sometimes even faint. However, when he is under the influence of Hysteria Berserk, all of his bottled up feelings including rage are released and set free. Kinji is able to remember everything he said while in Hysteria Mode, and gets really embarrassed whenever he looks back on it, saying he feels like a complete idiot.
Despite his snarky, pessimistic attitude, deep down Kinji is a kind and caring person with a strong sense of justice as a Tohyama, even though he hates it. He believes the powerful should not harass those without power and will follow the rules of law even if his life is at risk for the sake of order. Kinji, to the dismay of Aria, prefers a non-violent approach when facing the enemy before attacking. Also, as noted by Aria, Kinji will show world-class bravery in the face of great danger. Kinji also doesn't believe in holding grudges against people for past actions, as he considers it to be a waste of time, and has even shown reluctance towards killing animals such as wolves.
After Kinji finally transfers out of Butei High and experiences how unfulfilling civilian life is, he comes back and embraces being a Butei as it was the only thing he was good at to a certain extent. However, he still wishes to be a normal Butei, which he has found impossible after becoming known to the U.S. military, Intergovernmental Armed Detective Alliance (IADA), and other governments and groups based his battles since meeting Aria.
Kinji was born as the youngest child of the Tohyama family before Kinzou, Kaname, and Kanade were created. As a child he learned his family arts and Hysteria Savant Syndrome from his older brother, Kinichi. He became very proficient at his family's craft, much to the admiration of his older brother. Also, he often made regular visits with his family to the Hotogi Shrine, where on one occasion he met and befriended Shirayuki. Often times they would play together and, despite knowing the punishment Kinji would receive, he brought her to the world outside of the Hotogi Shrine. However, during Kinji's youth, his parent died sometime and was raised by Kinichi.
During middle school, he and Shirayuki parted ways, so he took on the role of becoming a Butei like his older brother by entering in a school meant to train Butei's. It was during this time period where he met Kikuyo Kagataka, who was hiding and crying after being bullied, while cleaning. Kinji would comfort her and under the influence of HSS, would get the girls who bullied her to apologize. However, school life would be anything, but easy for him after this due to the girls in his class, including Kikuyo, investigating him and exploiting his HSS ability in order be their personal "Ally of Justice."  This would have a lasting effect on Kinji, as he would develop a complex against women and using his family's special talent, especially after being ganged upon after trying to stand up for himself each time. Despite, what Kikuyo did to Kinji, he did stand up for her when she was accused of stealing money from the classroom lock box and resulted in her not using his abilities against him for the remainder of her stay in middle school. Also, while in middle school, Kinji encountered an underclassmen, Hina Fuuma, where he fought her in a duel and beat the her, earning her respect eventually culminating in her recruitment as his Amica later on.
Upon graduating middle school, he enrolled in Tokyo Butei High as a member of the Assault department, much like his brother. When taking the entrance exam for the school, he met Reki for the first time at Futoukita platform on Academy Island. Later, Kinji would meet Riko Mine and Ryou Shiranui for the first as well as Shirayuki again, who put Kinji under Hysteria Mode before taking the Assault Exam. Then, while under the influence of Hysteria Mode, he took the Assault Exam in a 14-story building where he single-handedly caught all the other Assault exam candidates and even defeated the five instructors hidden in the building earning him an S-Rank. Later, he would get into a Lumberjack duel with Gouki Mutou over Shirayuki resulting in them becoming friends. It was during this time period that Kinji would work together quite a bit with Reki, where they were known as the "Golden Duo." 
However, school life again would take a turn for the worse for Kinji because his older brother was reported as killed in action from the Butei Killer, where despite saving everyone on board, Kinichi was ridiculed for losing his life and Kinji became the target for the ridicule as well by the media. After losing his only family, Kinji was forced to suffer alone and harbored a deep hatred towards the Butei for causing Kinichi to lose his life. This would cause him to transfer out of Assault to Inquesta, throw away his family heritage, let his reputation to those outside of Assault to plummet severely, allow his prestigious S-Rank to drop to E-Rank, and sought to transfer out of Butei High altogether into normal life.
- Kinji's name broken means gold (kin) second son (ji) as a reference to being Konza Tohyama (Golden Cross) second son.
- Chugaku Akamatsu's next light novel series, Yagate Maken no Alicebell; share the same universe where the protagonists crossover at some point.
- Its revealed that three years later from the novel series, Kinji enrolled into Tokyo University, while a member of the Security Police.
- In Volume 12, Kinji would succeed in his goal of transferring out of Butei High, but would return in Volume 13, Chapter 1 after learning he could not live an ordinary life.
- Most of the enemies Kinji has fought have been girls.
- Kinji's desire to be a normal Butei can be compared to Harry Potter's desire to be a normal wizard i.e. not "normal" in the traditional sense, but not the centre of attention either.
- (To Aria) "Butei Charter, Article 1: Trust your friends and help when they need it. I put my trust in you, Aria. Now it's time for you to put your trust in me for a change."
- (Kinji commanding Kou): "Don't look this way. If I decide that you're getting ready to fire a laser, I'll shoot. Butei Law prohibits killing. But you're not human, are you. Raise both of your hands slowly--" (Volume 13, Chapter 3)
- (Kinji calming down a crying Kou): "You're hungry, aren't? Me too. Have some of this. [Banana]" (Volume 13, Chapter 3)
- (Kinji to Kou, who is willing to die): "No that...it was only a threat..I'm mad, but I won't go as far as killing you. Don't cry. Please don't." (Volume 13, Chapter 3)
- (Kinji fighting back at Aria): "This is my first time overseas! I didn't study abroad like you!...You're the one that's fired! I'll defeat Ranpan by myself." (Volume 13, Chapter 3)
- ↑ Volume 26 Summary
- ↑ Volume 27 Summary
- ↑ Volume 13, Chapter 3
- ↑ Volume 13, Chapter 1
- ↑ Volume 12, Chapter 4
- ↑ Volume 11, Chapter 1
- ↑ Volume 12, Chapter 1
- ↑ Short Story Collection: Heroine's Asort, X-05