Wandering the vastness of space is the Sky Drifter; an academy reserved for the best students in the known universe. Seven is such a student, gifted in strategy and Sphere. Living happily on board with his friends Iris and Pi, Seven takes on his rival and visits planets for exploration and competition. Everything is the way he likes it, until he sees a mysterious girl in a red coat, who reveals to him a secret that will bring everything he thought he knew crashing down around him.