Hachiman Hikigaya, a cynical and socially isolated high school student, is forced by his teacher to join the Volunteer Service Club, a school group dedicated to helping students with their problems. The club is run by Yukino Yukinoshita, a brilliant but aloof classmate who shares Hachiman's disdain for superficial social interactions. Despite their contrasting personalities—Yukino's perfectionism and Hachiman's self-deprecating pragmatism—they form an uneasy partnership. The dynamic shifts when Yui Yuigahama, a cheerful and popular girl, joins the club, creating a trio with contrasting worldviews.

The series explores the complexities of human relationships through the club's activities, as the trio assists classmates with personal and social dilemmas. Hachiman's unorthodox methods often involve self-sacrifice, reinforcing his belief that genuine connections are rare and that people are inherently selfish. Yukino, while critical of his approach, gradually begins to understand his perspective, while Yui serves as a bridge between the two, offering empathy and emotional insight. Over time, the characters confront their own insecurities and vulnerabilities, revealing deeper layers to their personalities.

As the story progresses, the relationships among the trio evolve, with underlying tensions and unspoken feelings coming to the surface. The narrative delves into themes of loneliness, self-worth, and the difficulty of authentic communication. The second season introduces new challenges, including the arrival of other characters who further complicate the group dynamics. The series culminates in a resolution that addresses the characters' growth and the evolving nature of their relationships, offering a nuanced portrayal of adolescence and the struggles of forming meaningful connections.