Oniai Main Characters
- After six years of living separately, brother and sister Akiko and Akito Himenokouji are finally reunited. The two used to be quite close, until their parents died and they were sent to live with separate foster families. Now the two can live together and go to the same school as brother and extremely loving sister! It doesn’t take long before it becomes abundantly clear that Akiko has a huge brother complex. Unfortunately for Akiko, her brother only sees her as a little sister he must protect.
- But that won’t stop her from trying to win her brother’s affections! Things are only complicated when more girls move in with the siblings, making Akiko even more determined than ever to keep her brother’s eyes only on her. That’s tough to do with other girls flaunting their swimsuit-clad bodies at Akito, fighting over who gets to take care of him, and otherwise meddling in Akiko's plans for her brother. This is going to be one fun household…!
- The characters in the series include but are not limited to:
- Spoiler ALERT!!!
Akito Himenokoji[]
He is the brother and love interest of Akiko
Akiko Himenokōji[]
Akiko Himenokōji (姫小路 秋子 Himenokōji Akiko)
- Voiced by: Ibuki Kido
The main heroine and the Saint Liliana High School two year student. Akiko is Akito's sister and has a pretty appearance and polite manners. Akiko was adopted by the Arisugawa family when she and Akito were separated after their parents died. She has very serious brother-complex and is taking very active way to seduce Akito. She is also very proud of her brother complex and makes no effort of concealing it.
She is the secretary of Saint Liliana High School student counsel, but is very reluctant when Akito interacts with other student counsel members.
She doesn't know that Akito has no blood relationship with her and believes that they are twins; according to their deceased mother, Akiko will probably sexually assault her brother once she learn the fact. Even for, now, believing that they are blood related siblings, and respecting her brother's will is the only barrier that stops her from doing so.
She is a fan of Kōichirō Shindo, and is wishing her brother to be as aggressive as the brother in Kōichirō Shindo's novel; however she hasn't notice that Kōichirō Shindo is her brother Akito, and the beginning of Kōichirō Shindo's novel is based on their relationship. It is hinted that Akito actually feels the same way about Akiko but denies it.
[]
(那須原 アナスタシア Nasuhara Anasutashia)[]
- Voiced by: Minori Chihara
Saint Liliana High School two year student and the vice-president of the student council, the daughter of the owner of the Nasuhara industry, a world-wide company. Anastasia has Russian and American parents and has blonde twin dragon tails. She has a cold personality and often asks strange questions, such as asking Akito if he is a cherry boy when they first meet. She is the rival of Akiko and is proud that she wins a small bit on almost everything, including height, grades, breast size, rank during miss Saint Liliana High School election, and student council rank. However, she, is extremely weak at house chores due to her wealthy family, to the point that she will gladly admit it and escape her chores. She also loves cute things, and not only keeps lots of plush dolls in her room but also love to play with Arisa.
Despite being a rival of Akiko, she goes very well with Akito and confessed to him on his first day at school. Although Akito haven't got a chance to answer due to the chaotic situation that the confession brings on afterwars. She demands Akito to call her Anna, but laugh at him for calling a girl as "hole" (which sounds similar to Ana in Japanese) whenever he does so.
Ginbei Haruomi Sa[]
Ginbe Haruomi Sawatari (猿渡 銀兵衛 春臣 Sawatari Ginbee Haruomi)
Akito's childhood friend. Akito constantly tried to get Ginbe to be his friend, but she would keep trying to avoid him. When he visits her house, they finally settle with being best friends. Just as they did, Akito tries to get Ginbe to take a bath with him, not realizing she was actually a girl, due to her acting like a boy and her boyish name.
She has a habit of mumbling about Akito's unawareness whenever Akito overlooks her feeling.
Arashi Nikaidō[]
Arashi Nikaidō (二階堂 嵐 Nikaidō Arashi)
- Voiced by: Eri Kitamura
Saint Liliana High School two year student and the president of the student council, Arashi has a ponytail and often wearing an eyepatch on her right eye. She also often carry a real katana around.
She has 1st grade on 3rd year and is powerful on leadership, that she can not only handle most student council chores by herself, but also take control of most of the school's activity.
She is bisexual and is very aggressive on lust, that she has over 30 lovers, this also give her a nickname: "predator". However, later in the story she decided to separate peacefully with her lovers and aimed to seduce the entire student council as her harem first.
She is actually the cousin of Akito before his adoption by his parents, she also knows that Akito is adopted by his family, and decided to support him if she can. She knows that Kōichirō Shindo is Akito's pen name.
Arisa Takanomiya[]
Arisa Takanomiya (鷹ノ宮 ありさ Takanomiya Arisa)
The daughter of Akito's adopt family and proclaims herself as Akito's fiancee.
Arisa is a genius that despite only being 12 years old, has already graduated from a famous university, and her essay is published in multiple famous professional magazines.
Arisa is very proficient at house chores and is a excellent cook. At the end of the 4th novel, she moved to live with the student council members as the new manager.
While most student council members refer that the engagement doesn't count due to her age, Akiko still viewed her as a love rival. However, after an argument about who is better for Akito, the two worked together as they noticed that Akito see both of them as his sisters.
She has a habit to go silent and showing emotions on her face, which is so cute that people who see it can't resist accepting her will.
Jinno Kaoruko[]
Kaoruko Jinno (神野 薫子 Jinno Kaoruko)
Kōichirō Shindo's personal editor. Kaoruko worries that Akito has sister complex and tries to fix the situation. Kaoruko worries about this is because of the way Akito writes about BroXSis doujins. The two main characters in his novel even sharing a similar name to his and Akiko.
She tries at first to seduce Akito at the office when they were alone together, but was mistaken by Akito as Kaoruko imitating a story that he read. Failing at the seduction she goes to the dormitory to find out and confirm her suspicions.
When she meets Akito's sister Kaoruko concludes that it's a Brother with a sister complex and a sister with a brother complex making it even more dangerous.