Stratos 4 follows Earth's layered defense against catastrophic meteorites. The first line of protection consists of Comet Blasters stationed in orbit; they launch nuclear warheads from spacecraft to intercept incoming rocks. If the explosions generate dangerous debris, the second line, Meteor Sweepers, deploy from ground airbases in hypersonic aircraft armed with specialized missiles to clear the fragments. Mikaze, a troubled youth, is a trainee pilot in a Meteor Sweeper squad who aspires to join the elite ranks of the Comet Blasters. The series chronicles Mikaze and her teammates as they confront training hardships and personal growth while defending Earth from the looming celestial threats.