- Alexis "Alex" Roberts
- Morgan's "yaoi-pet", and perhaps the more level-headed between himself and Sandy. He is Sandy's friend and roommate. Along with Sandy, he was kicked out of his dorm because of Sandy's viewing of hentai anime, and the serving of Ramune which Dean Perkins mistook for an alcoholic beverage. It seems that Sandy is in fact Alex's best friend as Alex continues to stand beside Sandy in spite of all the adventures he has faced as a result of just being near Sandy. It also seems he has the exclusive attention of Morgan McKnight, who obviously has a crush on him. At one point in the story the removal of his ponytail makes him look sufficiently like a bishonen to cast a "fangirl" effect over the female cast. But as soon as a snippet of hair was cut, the effect was broken. Becomes stepbrother to Sandy and half-brother to Angela after his father marries Sandy's mother halfway through the series. Marries Morgan in the epilogue and has three kids with her.
- Sandy Grayson
- Sandy is the owner of Echiboo the hamster, and is also Alex's friend and roommate. Between himself and Alex, Sandy seems the larger otaku and is much more immature. Sandy is also the one that Jessica seems the most interested in, as she calls him "tiger" and teasingly flirts with him. Sandy appears to be a fan of almost all aspects of Japanese culture, or at least the otaku culture as is seen by his drinking of Ramune while viewing anime(he has a Sailor Moon shrine in his room), and likes to imagine different anime scenarios happening in real life. Has a strong dislike of corn after viewing Boku no Sexual Harassment's infamous porn scene involving corn. Becomes stepbrother to Alex and half-brother to Angela due his mother marrying Alex's father. In the epilogue he winds up marrying Maria and has two kids named Helena and Victor.
- Echiboo is Sandy's pet hamster. Morgan calls him a "panty hamster" because of the critter's obsession with panties. Echiboo seems to have taken a strong liking to Elle, or at least her panties. He is also one of the causes (by taking the Deans toupee) of Sandy and Alex's need to find new lodging, which eventually led them to Aoi House. Morgan likes to put a tiny camera on his head and let him run amuk, getting footage "of the ecchi kind." Echiboo's name is a pun of Ebichu, the hamster from the Gainax anime series Oruchuban Ebichu. His name also means "Perverted Fart" in Japanese, which is appropriate considering his obsession with panties. Has an attraction to Luna-P (who spurns him at first) and defies all laws of science by having a half pig-half hamster offspring with her called Diana. In the epilogue, he becomes a famous movie star thanks to his role in "Echibond".
- Elle Mathers
- The most mature of all the girls and very ill tempered. She comes from a wealthy family and continually acts upset about having Sandy and Alex as a part of Aoi House. She does wear a very interesting costume shortly after their first arrival however and seems to (barely) mellow down toward them as they become part of daily Aoi House life. She even began to develop a crush on Alex, but those feelings ended when he and Morgan became an item. Elle is on the tennis team. In the epilogue, she becomes an "Echi-Bond" girl and a successful actress.
- Nina Parker
- Nina is the most nonchalant member of Aoi House. She is also seemingly the least concerned about having two straight male housemates, as she at times continues to walk around without her shirt on regardless of the fact that she now has two straight male housemates. She also makes a habit of smoking where she is not supposed to. She is also a member of the swim team and practices synchronized swimming. Adam Arnold stated that Nina is the most "macho" of the Aoi House girls, and she also has the smallest bust. Nina apparently works at Sandy's and Maria's bookstore in the epilogue, but since she is still a slacker, Helena and Victor seem to do her job for her. This attitude is most likely why they let Sanae drag off Nina from time to time.
- Morgan McKnight
- The most energetic of the group, Morgan is a very hyper girl who seems to be on a continual sugar high and loves candy. Morgan has a playful, childlike innocence about her and how she interacts with Sandy and Alex. In her first meeting with them she claims Alex as her "yaoi pet" and later uses something of Elle's to lead Sandy and Alex on a wild chase that ends in the girl's locker room. Her closest friend who is not an Aoi House member seems to be the mysterious "Oniisan" who she doesn't seem to hesitate in telling her secrets, almost as she would to a diary. Morgan also continues to demonstrate, both in her actions and what she tells her "Oniisan", a very strong attraction to Alex. She is much less energetic when talking to her confidant. She and Alex ultimately start dating in the finale, and they get married in the epilogue with three kids named Timothy, Harley and Ivy. However, married life doesn't entirely take away her mischievous side, as she buys her young son yaoi manga, much to Alex's chagrin.
- Jessica Kim
- Jessica is a Korean-American medical student often found wearing her nurse outfit, the subject of Sandy's fetishes. She, along with Morgan, accepts Sandy and Alex joining Aoi House. Jessica is almost as playful as Morgan and joins in on one of hers schemes while helping to defend the ever hyper Morgan's desire for candy; both of these might be why she seems to be one of the few that can "control" Morgan. She is very motherly and also teases Sandy, which causes him many a nosebleed. However, she allows Maria and Sandy to hook up during the Con Caper. At this point, she also seems to develop a crush on Mason Blue. She has three little brothers. She achieves her goal of becoming a nurse at Seattle Grace Hospital in the epilogue, where her co-workers and child patients are very fond of her.
- Maria Ortega
- Along with Sandy and Alex, Maria is one of the newest members of Aoi House. Of Latina descent, she is a little self-conscious about her uncommonly large bust. She is happy to be in Aoi House, and is friendly toward Sandy and Alex, who once helped her shortly after they all joined. Her parents own a local Mexican restaurant which is a place she uses along with the other members of Aoi House to celebrate the new members. She eventually develops feelings for Sandy, whom she marries and has kids with in the epilogue. They run a bookstore called "The Bookcave".
- Somewhat of a mystery for most of the series. "Oniisan" seems to be the one that provides Morgan with an amazing amount of technological equipment including an "Ecchi-cam", a camera that can be strapped to Echiboo's head. "Oniisan" is also possibly Morgan's closest and only true confidant, and has counseled her, and Elle, on their respective attractions to Alex. At the beginning, it was not certain who or what Morgan's Oniisan was, though, Oniisan was eventually revealed in "Diary Room Antics" to be human. The previous theory was that he was some sort of computer (an obelisk labeled "Sound Only", a reference to the anime Neon Genesis Evangelion) with various sound and visual links throughout the house. Oniisan means "big brother" in Japanese, and all the members of Aoi House (and former member Carlo) address him as "oniisan." For the majority of the series, Alex and Sandy are unaware of Oniisan's existence, and the girls of Aoi House seem either unwilling or just have neglected to enlighten them. The top half of his face is always hidden; in Aoi House In Love! Vol. 1, he cosplayed as Tuxedo Kamen of Sailor Moon, so his eyes would be hidden; he later judges a cosplay battle between Aoi and Uri Houses and the UASOS Brigade wearing sunglasses. It has recently been revealed that Oniisan is actually Elle's brother and that his real name is Jacob. As it turns out, he is the one behind Aoi House's creation, whereas Carlo just pitched the idea to him after reading one of his flyers. Jacob is apparently the owner of a production company that was looking to make a new reality series, and with Carlo's suggestion, Aoi House came to fruition. He continues his Aoi House series in the epilogue.
- Aoi House's (Yaoi House's) homosexual transvestite founder. When Sandy and Alex first meet him/her s/he is dressed as a woman complete with wig and skirt. When the girls arrive and inform them of who Carlo is both Sandy and Alex shockingly learn that the one they thought was a "she" is in fact a "he". It is interesting that though they both have never met him/her, s/he clearly knows about them, indicating that the girls of Aoi House still keep close contact with their former founder. Carlo's face has stereotypical macho qualities. S/he also finds Alex very attractive and went on a date with him when Alex lost a bet. S/he winds up dating a silent boytoy named Rocky, whom s/he ultimately marries in the epilogue.
- Mr. Perkins
- Dean of the University. Echiboo stole Mr. Perkins's toupee, causing Sandy and Alex to search for new housing, which eventually lead them to finding Aoi House. He continues to be somewhat of a problem for Sandy and Alex; he keeps a close on eye them because of the trouble they caused in the past. Mr. Perkins can occasionally be found watching the synchronized swim team practice and talking to the swim coach, Ms. Addison. The epilogue just states that he's on the way to a coronary.
- Ms. Addison
- Coach of the women's synchronized swim team. Goes on to become an Olympic Swimming Coach in the epilogue.
- David, Daniel and Danny
- The little triplet brothers of Jessica. During the epilogue, it turns out that one of them becomes a "rebel" with black clothes and nail polish, along with a spiked collar and a mohawk, whereas the other two dress in prep school clothes.
- Uri House
- Aoi House's rival from Lawndale State University. Their name is based on Yuri, Jessica earlier stating they heard of Aoi House and did a Yuri rip-off. Its current members are:
Mason Blue – The de facto leader of the club. While he does not actually have a definite ending in the epilogue, a man with his earrings greets Jessica at Seattle Grace Hospital with a stethoscope around his neck.
A hooded boy named Kevin Cardenas – In charge of their AMVs and has a thing for Morgan (calling her "McCutie") as well as any girl he sees. Moves to Tokyo in the epilogue just for the girls
A boy with glasses named Dale Stevens – The club's artist. He gets roped into moving to Tokyo along with Kevin in the epilogue.
The open lesbian Sanae – Has a crush on Nina, as well as calling out that Maria's breasts were bigger than Kimberly Ann's. She kissed Nina at one point during the Con Caper, and somehow got both her and Elle into bed (much to their horror when they wake up the next morning) after the epilogue.
- "Sandy Grayson" who's surname is taken from Dick Grayson, the original Robin.
- "Morgan McKnight" who's surname is actually taken from the nickname for Batman who is known as The Dark Knight.
- Alex and Morgan's children, "Harley", "Ivy", and "Timothy" are named after Pamela Isely a.k.a. Poison Ivy, Harley Quinn, and Tim Drake a.k.a. the third Robin.
- Sandy and Maria's children, "Victor" and "Helena," are named after Mister Freeze and Helena Bertinelli a.k.a. the Huntress.
- Sandy and Maria's bookstore, Bookcave, is a reference to the Bat Cave.
- New Aoi House member "Stephanie Kane" is named after Stephanie Brown (a.k.a. The Spoiler) and Bob Kane, the creator of Batman. Her last name may also be a reference to the second Batgirl Cassandra Cain. Stephanie also has a pet bat named Babs, which is a common nickname for Barbara Gordon.