Homeless and fresh out of employment, Mito Yamamoto faces familiar loneliness and despair. Luck is simply not on Mito's side; when he stumbles upon a cafe and cuts his hand, a strange server named Ruka Saotome licks the blood from his wound and even dramatically retches at its apparent disgusting taste. Offended and dispirited, Mito runs off to a bridge, hoping to put an end to his misery. But when Mito accidentally slips, he is miraculously saved by Ruka, who reveals he is a vampire. Unable to drink blood from just any woman for mysterious reasons, Ruka proposes that Mito become his thrall—a vampire's human servant and primary source of food. In this deal, Ruka will shower Mito with love to sweeten his blood, and Mito will gain a warm place to call home. However, there is an issue: Mito is a girl! Concealing her long, flowing hair and feminine body, Mito readily takes this chance and enrolls in the Hijirigaoka Boys' High School while working part-time at the cafe with Ruka. But the more Mito's bond with Ruka deepens, the more she struggles to hide her secret.

In the studio of the morning childrens' show "Together with Mama," a crew of miserable adults prepares their facades of amicable smiles and cheerful exteriors to educate a group of innocent preschoolers. In the middle of it stands Uramichi Omota, a former gymnast who can't help but bring the kids down to earth by revealing the harsh and depressing reality of adulthood, even in front of the rolling cameras. Behind the scenes, Uramichi's much-desired peace is disturbed by his two bothersome juniors who work as the show's rabbit and bear mascots and singers: Utano Tadano, a woman who only wishes to get married; and Iketeru Daga, a handsome man with a crass sense of humor. From smoking and exercising to nihilistic outbursts, everyone's big brother Uramichi always brings up the not-so-moral side to his life lessons.

Haruka Shinozaki has been interested in the class representative, Akiho Kousaka, since his first year in high school. She is attractive, good at sports, and is an all-around model student. Since they are in the same class this year, Shinozaki decides to confess his feelings—and, to his shock, Kousaka agrees to be his girlfriend! However, he finds that Kousaka is a bit stranger than he first thought: this seemingly perfect girl has never been in a relationship. But even though she is inexperienced, she vows to please Shinozaki in every way she can... such as learning multiple sex positions or his fetishes. Shinozaki tries to assure her that her studies into such subjects aren't necessary, but Kousaka devotes herself to making him happy in more ways than one.