Secret of the Golden Coin (1958)

A princess finds life behind the protection of her brother and the high walls of the mansion to be quite dull, so she takes on another identity and lives in a small house in Edo pretending to be a singer but all the while she is actually a Shogunate Detective. Framed by a crooked magistrate for a crime she did not commit, Oshichi must clear her name of false charges after a woman helps to lead a prison break of the notorious Oshu Remnants. Meanwhile the magistrate, Lord Kai, conspires to be rid of her brother, Clan Elder, Lord Abe Iyo. Her only clue is an ornate dagger with a handle made of golden coins.