"Stratos 4" is a science fiction anime series set in a near-future Earth where humanity faces the threat of meteor showers caused by fragments from a disintegrating comet. To combat this, the Orbital Defense Program (ODP) was established, deploying space stations equipped with advanced technology to intercept and destroy incoming meteorites before they reach Earth. The story primarily centers on Mikaze Honjo, Shizuha Fujima, Ayamo Karigari, and Kotona Mishima, four young women training as Comet Blasters, pilots tasked with protecting the planet from these celestial threats.

The narrative begins with Mikaze, a skilled but somewhat aloof pilot, being transferred to the Shimojishima Base, a training facility for Comet Blasters. There, she joins Shizuha, Ayamo, and Kotona, who are already part of the team. Each character brings distinct personalities and skills: Shizuha is the disciplined and serious leader, Ayamo is cheerful and energetic, and Kotona is quiet and reserved. Together, they undergo rigorous training to prepare for their missions, which involve piloting high-tech aircraft called "Stratos" to intercept meteorites in Earth's upper atmosphere.

As the series progresses, the focus shifts between the characters' personal growth and their professional challenges. Mikaze struggles with her past and the pressure of living up to her family's legacy, while Shizuha grapples with her responsibilities as a leader. Ayamo and Kotona also face their own insecurities and aspirations, adding depth to their interactions and teamwork. The series balances these character-driven moments with action-packed sequences of meteorite interception missions, showcasing the technical and strategic aspects of their work.

A significant subplot involves the discovery of a massive meteorite fragment that poses an unprecedented threat to Earth. This event tests the team's abilities and forces them to confront their fears and limitations. The series also explores the broader implications of the ODP, including the ethical and logistical challenges of protecting the planet from cosmic dangers.

"Stratos 4" combines elements of science fiction, drama, and action, with a focus on the camaraderie and determination of its main characters. The narrative emphasizes teamwork, perseverance, and the importance of facing challenges head-on, all set against the backdrop of a high-stakes mission to safeguard humanity. The series is structured into two main parts: the initial 13-episode run, which focuses on the team's training and early missions, and a sequel OVA series, "Stratos 4: Advance," which delves deeper into their roles as seasoned Comet Blasters and introduces new challenges.