"Fight! Osper" is a sports anime centered around the competitive world of professional wrestling, blending athleticism, drama, and personal growth. The protagonist, Osamu Takeda, is a young man with a passion for wrestling, inspired by his late father, a former professional wrestler. Osamu joins the fictional wrestling organization "Global Wrestling Federation" (GWF) to pursue his dream of becoming a champion. The series explores his journey from an inexperienced rookie to a formidable competitor, highlighting the physical and emotional challenges he faces along the way.

The narrative is structured around Osamu's progression through the ranks of the GWF, with each arc focusing on key matches and rivalries. His primary rival is Kenta Shiraishi, a seasoned wrestler with a cold, calculating demeanor, who serves as both a mentor and antagonist. Their dynamic evolves from hostility to mutual respect as they push each other to their limits. Other significant characters include Aya Fujimoto, a determined female wrestler who challenges gender stereotypes in the sport, and Hiroshi Matsuda, a veteran wrestler who becomes a father figure to Osamu.

The series delves into the intricacies of professional wrestling, emphasizing the importance of strategy, technique, and showmanship. It also addresses themes such as perseverance, camaraderie, and the sacrifices required to achieve greatness. The matches are depicted with a mix of realism and theatricality, capturing the spectacle of wrestling while grounding it in the characters' personal struggles. As Osamu grows, he learns to balance his ambition with humility, earning the respect of his peers and fans.

"Fight! Osper" balances intense action with character-driven storytelling, offering a compelling exploration of the world of professional wrestling. The series appeals to both fans of the sport and those interested in stories of personal triumph and resilience.