"Kujibiki Unbalance" centers around a high-stakes lottery system at Rikkyoin High School, where students are randomly assigned roles and responsibilities that significantly impact their academic and social lives. The narrative primarily follows Chihiro Enomoto, a first-year student who, through the lottery, becomes the class president. Alongside him are Tokino Akiyama, a determined and resourceful girl who becomes vice president, and Izumi Tachibana, a quiet and reserved classmate who serves as the secretary. Together, they navigate the challenges of their new roles while managing the expectations and pressures of their peers.

The story unfolds as the trio is thrust into organizing and participating in the school's annual Kujibiki Unbalance tournament, a series of competitive events that determine the school's leadership hierarchy. The tournament is a mix of physical, intellectual, and strategic challenges, with each round presenting unique obstacles that test the participants' abilities and teamwork. As the competition progresses, alliances are formed, rivalries emerge, and personal motivations come to light, adding layers of complexity to the narrative.

Chihiro, Tokino, and Izumi must confront their own insecurities and past experiences while striving to lead their class to victory. The series explores themes of friendship, perseverance, and the unpredictability of fate, as the characters grapple with the consequences of the lottery system and their own choices. Supporting characters, such as the enigmatic Kaoruko Yamada and the ambitious Renko Kamishakuji, further enrich the story by providing additional perspectives and challenges.

The plot is driven by a combination of interpersonal dynamics and the escalating intensity of the tournament, culminating in a climactic final round that determines the future of Rikkyoin High School. Throughout the series, the characters' growth and development are closely tied to their experiences in the tournament, highlighting the impact of their decisions and the importance of collaboration in overcoming adversity. "Kujibiki Unbalance" presents a compelling blend of competition, character-driven storytelling, and thematic depth, making it a notable entry in the school-life and tournament genres.