The characters in the series include, but are not limited to:
- Nao Takanashi (高梨 奈緒 Takanashi Nao)
- Voiced by: Eri Kitamura
- Nao, the protagonist of the story, is the adopted daughter of the Takanashi family and secretly loves her brother Shūsuke, going as far as to know everything about him to an obsessive degree. Ten years ago, she was in a car accident which killed her true parents and caused her to lose her memory, and she had only recently learned the truth. She goes to various lengths to make sure Shūsuke becomes attracted to her, such as throwing out his non-incest porn, and becomes particularly annoyed with other girls aiming for his affections. Her real name is never mentioned and her current name is the same as her deceased biological mother.
- Shūsuke Takanashi (高梨 修輔 Takanashi Shūsuke)
- Voiced by: Toshiyuki Toyonaga
- Shūsuke is the son of the Takanashi family. He is rather perverted, often keeping large abundances of porn magazines and always looking for panty shot opportunities. Recently he continues to use term which "not betraying Nao" implying he loves her, or at least wishes to have her see him as a good older brother. He does admit to feeling some interest in Nao, not brother–sister interest, but girlfriend–boyfriend interest. He is not aware of Nao's knowledge of either the truth about their relationship or the fact she knows about all his dirty habits. He is quite the heavy sleeper, making Nao wake him up almost daily for school, though Nao does likes this way for she can do the things she wouldn't normally do to him when he is awake, in short this is when she shows her true self.
- Iroha Tsuchiura (土浦 彩葉 Tsuchiura Iroha)
- Voiced by: Marina Inoue
- Iroha is Shūsuke's childhood friend before Nao's adoption. Having played Doctor with him a lot as a child (which was Shūsuke's excuse to see her naked), she claims that she is Shūsuke's lover and constantly makes advances on him. She is also something of a stalker, watching him in his house through a telescope and using night vision goggles to stalk him. She is even called a "Genuine Stalker" due to her very detailed reports of Shūsuke's late night actions and activities. Though she did say that Nao is the most wicked stalker but when only when she said it to herself. She is in constant competition with Nao over Shūsuke's affections, though they occasionally work together when someone else catches his eye. Oddly, despite the fact she has openly stated she is willing to have sex with and even initiating the first move, Shūsuke, he seems to not want this. Though it is hinted this is due to guilt, believing his actions made her this way.
- Mayuka Kondō (近藤 繭佳 Kondō Mayuka)
- Voiced by: Kazusa Aranami
- Shūsuke's classmate and class president, with a strong interest in Boy's Love magazines. When one of her magazines is torn up by Shūsuke during a mix up with one of his, she makes him her 'pet', having him purchase more explicit BL magazines and review them for an unbiased opinion, though she interprets this as having a shared interest. Despite Shūsuke's perverse belief that she may ask him to do something perverted at some point, she seems to be oblivious to this, appearing to treat him more as a boyfriend such as making him bentos and coming to wake him up for school. Recently it is shown she has strong feelings for Shūsuke because of his apparent acceptance of her BL magazines. She soon becomes attracted to Shūsuke's pink and sensitive nipples due to the fact she has never seen a naked man before, though despite him being her pet, she doesn't use this to her advantage. Although she confesses that she has feelings for Shūsuke, albeit those of wanting to dominate him, she loses memory of the incident after being hit by a truck.
- Shūji Takanashi (高梨 修司 Takanashi Shūji)
- Voiced by: Hideki Ogihara
- Shūji is the father of Shūsuke whom seems to have some of his son's perverted nature, such as trying to take one of his son's confiscated magazines and when he took Nanaka in a porn movie on their first date.
- Nanaka Takanashi (高梨 菜々香 Takanashi Nanaka)
- Voiced by: Sayaka Ohara
- Nanaka is the mother of Shūsuke. Always sees her son as a perverted child.
- Hirono Kusuhara (楠原 尋乃 Kusuhara Hirono)
- Voiced by: Ryoko Shiraishi
- Hirono is a friend of Nao. Questions to why Iroha and Nao both love Shusuke.
Collectively known as the A.G.E. Explorers (AGE探検隊 All Genre Ero Tankentai ), these are Shūsuke's friends who together constantly seek out and share erotic materials of all kinds.
- Keiichirō Kishikawa (岸川啓一郎 Kishikawa Keiichirō)
- Voiced by: Shinnosuke Tachibana
- In the anime, it is implied that Keiichirō (K1ro) may have homosexual feelings towards Shūsuke, though this is merely daymares Shūsuke has due to the trauma he has developed by being forced to read BL books.
- Voiced by: Mitsuhiro Ichiki
- Shizuru (静留)
- Voiced by: MAKO
- A fictional character from a little sister themed eroge Shūsuke owns who often shows up in his perverted dreams, usually those brought on by near death experiences.
- Ran Yatagai (谷田貝 蘭 Yatagai Ran)
- Voiced by: Minori Chihara
- She is a cosplayer who goes under the alias 'Princess Leila' (or Layla) and is very into her roleplay, suggesting she has a very loose grasp of reality. She seemingly makes a move on Shūsuke, dubbing him 'her saviour', and puts him through many strange trials, which are later revealed to train him to act out a warrior role in a cosplay event.
- Rin Yatagai (谷田貝 凛 Yatagai Rin)
- Voiced by: Rina Satō
- Ran's older twin sister. She is often annoyed by her sister, who often calls her 'Clone'. Although she initially appears to help Nao stop Ran's crazy plans, it is later revealed that she is a lesbian who has become interested in Nao's lips as well as seems to have a harem of girls after her attention. In the end, she accidentally kisses Iroha and takes a liking to her instead.