Mayuyama Koji is an art restorer who works with antique dealers and museums nationwide in Japan. His unique skills allow him to flawlessly restore broken works to their former condition, earning him the nickname "God Hand." The practice originated from his father in the postwar period, when many antiques would be repaired secretly through underground means. The documentary THE UNKNOWN MASTER OF RESTORATION reveals the details of his techniques, as well as his mission not just to restore art, but to preserve it for generations to come.