Shougo Mikadono's father has just passed away, and now he must become the head of Mikadono Group, his father's company. After completing the training to take over, there is just one other stipulation he must adhere to: he will need to find a girl he loves at his new school and marry her by the time he graduates high school. Shougo transfers to Miryuin Private Academy, and it seems like he has many girls to choose from, such as Konoe Suruma, the class representative as well as his first new friend; Miyabi Kannagi, a standoffish but kind girl; Rinka Kunitachi, the student council vice president; Mei Sagara, who runs a cafe and dresses like a witch; and Mana Tendou, the student council president. However, there is a complication: one of them is his long-lost half sister, and he has no idea which one, so how can he become romantically involved with any of them? [Written by MAL Rewrite]

Kagemori Mamoru is a dowdy boy whose hair is disheveled and who wears thick glasses, but he is actually the son of a ninja family. They have protected their neighbors, the Konnyaku family, secretly for 400 years. Mamoru has personally protected their daughter, Konnyaku Yuuna, since they were in kindergarten. When Yuuna is in trouble, Mamoru puts on ninja suit and turns into a competent ninja to help her.

Taito has been really sleepy lately, and keeps dreaming of a female vampire who says she has given him her "poison." Sometimes he even thinks he hears her voice when he's awake. But after surviving an accident that should have killed him, Taito's world changes drastically and he realizes that his dreams are more real than he thought.

After losing his mother, 14-year-old Taro journeys to Tokyo to live with his grandfather. But he gets the biggest surprise when he discovers that his grandfather's home is a huge mansion with hundreds of beautiful maids ready to serve him. Making matters worse (at least for Taro, but not for our viewing) is that not only does he inherit the Hanaukyo mansion, he gets the services of all of the maids 24 hours a day, 7 days a week.