"Don't Call Us A JUNK GAME!" centers on a group of high school students who form an unlikely team to compete in a niche, underappreciated card game called "Junk Game." The protagonist, Haruto Saito, is a reserved and introverted student with a natural talent for strategic thinking. Despite his skills, Haruto has avoided competitive play due to a past incident that left him disillusioned with the game. His life takes a turn when he encounters Rina Takahashi, a spirited and determined classmate who is passionate about reviving the dwindling popularity of Junk Game at their school.

Rina convinces Haruto to join her in forming a club dedicated to the game, alongside other students who each bring unique strengths and personalities. These include Kenta Mori, a tech-savvy gamer with a knack for analyzing game mechanics, and Yui Nakamura, a quiet but observant player who excels in reading opponents. Together, they navigate the challenges of building a competitive team, balancing their personal struggles with their shared goal of proving that Junk Game is more than just a "junk" hobby.

The narrative unfolds through a series of tournaments and matches, where the team faces off against rival schools and seasoned players. Each match serves as a platform for character development, as the protagonists confront their insecurities, learn to trust one another, and refine their strategies. The story also delves into the history and intricacies of Junk Game, exploring its mechanics, lore, and the passionate community that surrounds it. Themes of perseverance, teamwork, and self-discovery are woven into the plot, as the characters strive to overcome both external competition and internal doubts.

As the series progresses, Haruto and his teammates grow not only as players but also as individuals, forging strong bonds and redefining their relationships with the game. The climax centers on a high-stakes national tournament, where the team must face their toughest opponents yet and prove that Junk Game deserves recognition and respect. The story concludes with a sense of accomplishment and growth, leaving room for potential future developments in the characters' journeys.