"Gundam Build Fighters Try" is set in a world where Gunpla Battle, a competitive sport using customized plastic Gundam models, has gained widespread popularity. The story centers on Sekai Kamiki, a martial artist with a passion for fighting, who transfers to Seiho Academy. There, he meets Fumina Hoshino, the captain of the school’s Gunpla Battle Club, and Yuuma Kousaka, a skilled builder but reluctant fighter. Together, they form Team Try Fighters to compete in the national Gunpla Battle tournament.

Sekai pilots the Build Burning Gundam, a model designed for close combat that aligns with his martial arts expertise. Fumina operates the Winning Gundam, which later transforms into the powerful Lightning Gundam, showcasing her strategic versatility. Yuuma, initially hesitant to fight due to past failures, pilots the Gundam Tryon 3, a model that reflects his creativity and technical skill. The trio’s dynamic evolves as they face various rivals, including Team Celestial Sphere, led by the enigmatic Wilfrid Kijima, and Team SD-R, which specializes in unconventional tactics.

The narrative progresses through their journey in the national tournament, highlighting their growth as a team and as individuals. Sekai learns to balance his raw fighting instincts with teamwork, Fumina gains confidence in her leadership, and Yuuma overcomes his self-doubt to fully embrace his role as a fighter. The series also explores the broader Gunpla Battle community, featuring cameos from characters in the previous series, "Gundam Build Fighters," and introducing new competitors with unique models and strategies.

As Team Try Fighters advances through the tournament, they encounter increasingly challenging opponents, culminating in a showdown with Team Celestial Sphere. The final battles test their resolve, skills, and the strength of their bonds. The series concludes with the team reflecting on their journey and looking forward to future challenges, leaving room for further exploration of the Gunpla Battle world.