An unexpected accident brings physics student Su Xingluo to live in the home of Shen Muchen, her roommate's older brother. He appears cold and aloof, but around her, he is awkward and gentle. He cooks for her when she gets hurt and quietly blushes at a simple word of concern. Under the same roof, their shared dream of exploring the stars gradually brings them closer. Until one day, she discovers that he is actually the person who guided her online six years ago to pursue her dreams—the one who drew Pluto to encourage her when she was most lost. It turns out their love had already been locked together like Pluto and Charon, quietly revolving around each other in the vast universe for six years.