In 2167, a supernova explosion engulfed the Earth with a wave of electromagnetic energy, turning the sky green and causing countless disasters. After recovering from that first wave, humanity started putting up defenses to protect itself, and by the year 2356, a network of six Foundations (orbiting space stations) now guards the Earth from a second supernova wave that is expected to arrive later that year. Each Foundation houses a high school for promising young space cadets, and eager 15-year-old Shima Katase has just been accepted to Stellvia, the 2nd Foundation. Making friends, going to class, learning to pilot light spacecraft -- it's all part of the high school experience, hundreds of miles above Earth aboard space station Stellvia.