The mikado of Japan: The emperor of Japan and the father of Nanki-Poo, the mikado is the law. In fact, “When [his] majesty says, ‘Let a thing be done,’ it’s as good as done—practically it is done—because [his] majesty’s will is law.”
Nanki-Poo: The son of the mikado, Nanki-Poo has fled the royal court because his father has promised him in marriage to Katisha. Nanki-Poo, however, loves Yum-Yum and has gone in search for her, disguised as a wandering minstrel.
Ko-Ko: The lord high executioner of Titipu (the highest rank a citizen can obtain), Ko-Ko was a cheap tailor who had been sentenced to death for flirting, until he was raised to his high position through “remarkable circumstances.” He is also engaged to marry Yum-Yum, even though she doesn’t love him.
Pooh-Bah: The lord high everything else, Pooh-Bah is “first lord of the treasury, lord chief justice, commander-in chief, lord high admiral, master of the buckhounds, groom of the back stairs, archbishop of Titipu, and lord mayor, both acting and elect, all rolled into one.”
Pish-Tush: A noble lord of Titipu.
Yum-Yum: A ward of Ko-Ko and sister of Pitti-Sing and Peep-Bo, Yum-Yum is in love with Nanki-Poo, even though she is betrothed to Ko-Ko, whom she doesn’t love.
Pitti-Sing: A ward of Ko-Ko and sister of Yum-Yum and Peep-Bo.
Peep-Bo: A ward of Ko-Ko and sister of Yum-Yum and Pitti-Sing.
Katisha: An elderly lady of the mikado’s court, Kathisha is in love with Nanki-Poo and has been promised to him by the mikado. However, Nanki-Poo does not return her love.