In 2015, the K-pop group TWICE burst onto the global scene with their iconic tagline, "One in a million, We are TWICE!" With hit songs like "CHEER UP," "TT," "What is Love?," "FANCY," and "Feel Special," they quickly won the hearts of fans around the world. This documentary chronicles their incredible ten-year journey, showcasing their tireless dedication, the thrill of international tours, and intimate reflections on their personal growth, friendships, and aspirations. As they celebrate a decade of success, the film features exclusive interviews and highlights the meaningful bond between TWICE and their devoted fans, 'ONCE.' On their milestone anniversary, 〈ONE IN A MILL10N〉 unveils the essence of TWICE—a truly unique group.