When mundane office worker Kiyoshi Adachi turns 30 years old, he discovers that he has gained the ability to read minds due simply to remaining a virgin for his entire life. The caveat, however, is that he must make physical contact with a person to know what they are thinking about. Adachi believes there is no real use for this power until he accidentally hears the thoughts of his coworker, Yuuichi Kurosawa. Charismatic and dependable, Kurosawa is the star of Adachi's team at work, earning praise and admiration from everyone at the office. But deep within, Kurosawa harbors an intense one-sided crush for the gloomy Adachi—a fact that Adachi only learns because of his ability, and knowledge he tries to respectfully disregard. As Kurosawa treats Adachi with kindness and affection he has never experienced before, Adachi finds it increasingly difficult to ignore his coworker's genuine advances.

Returning from their summer vacation, the students of Class 3-E at the prestigious Kunugigaoka Middle School find themselves up against unbeatable odds. Faced with the possibility of world annihilation, the students must come up with increasingly elaborate and creative ways to kill their teacher, the cunning yet optimistic and helpful Koro-sensei. However, eliminating Koro-sensei is not the only objective the students need to worry about. Gakuhou Asano, the academy's merciless and cruel principal, seeks to prevent Class 3-E's success by brainwashing his other hard-working pupils into ruthlessly competitive studying machines. Hostility begins to linger in the air as traitors and killers alike attempt to claim the bounty on Koro-sensei's head for themselves. Nagisa Shiota, one of Class 3-E's most skilled assassins, finds himself in the middle of the conflict. While he works to maintain his academic standing and prevent the end of the world, domestic affairs jeopardize his place in Class 3-E. Together with his dedicated classmates, he must now face the threats head-on.

Tennomifune Academy is an elite institution for the best and the brightest, with the exception of Class 1-7, the so-called Happiness Class. Each member of the classroom copes with personal misfortunes, and the special class is geared to help them move past their issues and find true happiness. After being accepted into the academy, An Hanakoizumi, Ruri Hibarigaoka, and Botan Kumegawa find themselves placed into the Happiness Class, plagued by dreadful luck, love problems, and bad health respectively. Alongside their classmates, they do their best to overcome the difficulties they are faced with in pursuit of a life filled with joy.

On the brink of extinction, mankind has downsized and now solely resides in the city-state of Flandore, living in cities encased by glass domes. Beyond the domes exist vicious lycanthropes who thrive in the darkness; among the citizens inside, a clear distinction between the nobility and commoners is in place. The blood of nobles enables them to utilize mana, granting them abilities that exceed human limits and greatly assist them in defeating lycanthropes. Already 13 years of age, noble Melida Angel has yet to manifest her mana, and attends an elite academy where she is mistreated for her lack thereof. In order to help her, Kufa Vampir is ordered by the Angel family to become Melida's tutor. While Kufa seems to be a mere mentor, an ulterior motive lurks behind his job—he is to assassinate her if he confirms that she does not possess mana. Kufa's investigation eventually leads him to determine he must eliminate Melida. However, Kufa is struck by her unwavering determination, spirit, and belief in herself when he witnesses her in a fight, choosing instead to offer a way she can manifest her magic. As Melida learns to use mana with the help of Kufa's teachings, Kufa forsakes his mission and jeopardizes everything to keep his discovery of Melida unknown to the Angel family and his own guild. However, both Kufa and Melida will soon realize that hiding their secret will not be the only challenge they face, as unforeseen trouble is waiting just around the corner.