Filled with an overwhelming sense of wonder for the world around her, Mari Tamaki has always dreamt of what lies beyond the reaches of the universe. However, despite harboring such large aspirations on the inside, her fear of the unknown and anxiety over her own possible limitations have always held her back from chasing them. But now, in her second year of high school, Mari is more determined than ever to not let any more of her youth go to waste. Still, her fear continues to prevent her from taking that ambitious step forward—that is, until she has a chance encounter with a girl who has grand dreams of her own.