Hekikai no AiON

Karin is a cute little girl who also happens to be a vampire…with a twist. Once a month, she experiences intense bleeding from her nose–we're talking gushers! In other words, she's a vamp with blood to spare, so rather than stealing blood from humans she actually gives her blood to them. If done right, this can be an extremely positive experience that benefits the "victim" as much as the vampire. The problem is that Karin never seems to do things right!

Hirose Goushi has a huge sister complex. So huge, he moves from his home town to Tokyo to attend Myouzen University in order to escape it! Three years later, Goushi's little sister Noa shows up and informs him that she's taking the Myouzen University entrance exam and that she will be moving in if she passed. Little does Goushi know, she has a similarly large (if not larger) brother complex. Read as Goushi attempts to hide his feelings for his sister, while she purposefully sets him up for failure.

Tsugawa Tatsuya just lost his parents in an accident… but he's trying not to let that keep him too down as he starts high school. While trying to obey his father's final wish for him to become an upstanding man, he ends up helping a girl who was being bullied. Despite her exceedingly cold nature, he just can't leave her alone… which may not necessarily be to his benefit, as he ends up getting wrapped up in a world where things like parasitic mind-controlling bugs exist...

Sadashima fell in love with a handsome senpai while she was in high school, but didn't have the guts to tell him before he graduated and moved away. When Sadashima graduates the next year, she follows her senpai, Shirahai, to Tokyo and manages to move in next door. She totally believes that the two of them can now hook up, and can't wait to knock on his door to 'coincidentally" find themselves neighbors. She's flabbergasted to find a woman answering Shirahai's door, and then blown away to find out the woman is Shirahai! He's had a sex change!