At fifteen years old, Mirai is a pretty but deeply pessimistic high school student whose greatest wish is to make a single true friend. Her antisocial personality has left her completely isolated, and she struggles to connect with others. On her first day of high school, she finds herself being persistently bothered by a university student when a boy from her own grade steps in to help her. Tohru Sumeragi is handsome, elegant, and bright, but he is also a complete airhead with a remarkably pure heart. Despite his charm, he has no friends either, largely because he comes from an extremely high-class family, and his social status creates a barrier between him and his peers.

Both Mirai and Tohru are inexperienced in the simplest of social bonds, lacking the basic skills needed to start a friendship. Mirai wonders if someone as different from her as the wealthy and naive Tohru could ever truly become her friend. The story is set in a contemporary Japanese high school, where the pair decides to begin their relationship by becoming friends first, navigating the awkward and unfamiliar territory of companionship. What follows is a romantic comedy about two deeply immature individuals learning how to interact with another person for the first time, as their clumsy attempt at friendship slowly blossoms into an even more awkward and innocent first love. The narrative focuses entirely on the evolving dynamic between the two leads as they overcome their social shortcomings together without significant interference from other characters.