A boy who loves the stars, Kōsuke, fails his high school entrance exam. At the backup school he reluctantly attends, he meets Natsuki from the track and field club. Kōsuke likens Natsuki’s dazzling, lively radiance to Sirius, the fiercely shining first-magnitude star. He believes he is nothing like Natsuki—just a faint, second-magnitude star with little presence… But the destinies of twinkling stars can change completely.