As a vampire, Luna Ishikawa can be considered a unique transfer student. With her cool demeanor, she has quickly become her class' center of attention. Normally, it would be nearly impossible for Tatsuta Ootori—a completely average guy—to ever interact with her. However, this changes when the two are unexpectedly paired together for cleaning duty! After Tatsuta spontaneously forms a friendship with Luna, his impression of her slowly crumbles: she is not the mysterious and collected girl everyone thinks she is. In fact, she is unable to even suck blood properly! Resolved to help Luna overcome her ineptness, Tatsuta proposes to become her practice partner. Pumping life into their mundane school days, the duo gradually works toward their delectable goal, improving Luna's blood-sucking skills with every bite she takes.

Being a girl of both spirit and human blood, eight-year-old Ellen has power over the elements—though not the traditional four-element kind. She has the power to transform her surroundings by manipulating the elements of the periodic table. On top of that, Ellen also has a great amount of scientific knowledge due to being a scientist in her past life. During the war against a neighboring kingdom, Rovel Vankreift, the hero of the Kingdom of Tenbahl and eldest son of house Vankreift—as well as Ellen's father—was fatally injured. However, the spirit who fought by Rovel's side, Lady Origin, brought him to her realm to save him from the clutches of death. Lady Origin, who happens to be the Queen of the Spirit Realm as well as Ellen's eventual mother, is one of the most powerful spirits in existence, making little Ellen quite powerful in contrast to her innocent looks. But even a family as happy as this one has its fair share of problems, as Ellen and her parents are forced to reconnect their old ties to the Vankreift household in order to defend their relatives' honor—all while hiding Ellen's dangerous existence from the public to preserve their undisturbed happiness.

Wealthy, handsome, and successful, Arthur Louis Zetes is no stranger to the greed of people. Constantly doubting those around him, he has no faith in humanity; thus, he makes a request for the perfect maid—a robot maid. However, his butler is unable to acquire such a servant due to technological limitations, so he finds the next best substitute. Marie Evans is a former child prodigy in martial arts known for her lack of expression. Drowning in debt, she readily accepts the offer to be a maid that acts like a robot. While Arthur is often blunt towards humans, he cannot help but dote on his personal robot; in turn, Marie is moved by his drive and consideration toward her.

With a smirk, Oota disregards his single-digit test scores and searches for a new source of amusement. He is soon captivated by his classmate Kashiwada, a mysterious student who consistently wears a blank face. Oota conspires to break her placid demeanor through scares and mischievous schemes, though his tactics always seem to backfire. Oota is known as the class clown and is constantly disciplined by his teacher, who claims his face gives it away. To no fault of his own, he lacks control of his emotions and facial expressions. Kashiwada, on the other hand, seems perpetually emotionless and unreadable—no one knows what she is thinking! Oota and Kashiwada are complete opposites, but that does not stop a unique relationship from developing between them. As they realize their feelings for each other, it raises an important question: do opposites really attract?