Full Synopsis
A year before the curtain goes up, Nanki-Poo, son of the Mikado of Japan, flees the imperial court to escape marriage with Katisha, an elderly lady. Disguised as an itinerant musician, he meets and falls in love with Yum-Yum, the young ward of Ko-Ko, a cheap tailor in the town of Titipu. Yum-Yum, however, is already betrothed to her guardian and Nanki-Poo leaves Titipu in despair.
Act I
The action takes place in the town of Titipu.
The curtain goes up on a group of Japanese nobles going about their business. Nanki-Poo, still masquerading as a musician, having heard the news that Ko-Ko has been condemned to death for flirting has hurried back to Titipu to try to claim Yum-Yum. Unfortunately he learns from Pish-Tush that, far from being dead, Ko-Ko has been reprieved at the last moment and appointed Lord High Executioner. There is worse to come as Pooh-Bah, the holder of every other major office of the state, informs Nanki-Poo that Yum-Yum and Ko-Ko are to be married that afternoon.
Ko-Ko appears, and recounts the story of how he became the Lord High Executioner. He seeks Pooh-Bah’s advice as to how much he should spend on his forthcoming wedding. Yum-Yum and her sisters, Pitti-Sing and Peep-Bo arrive with their school chums. Yum-Yum and Nanki-Poo are reunited and he tells her that he is the son of Mikado. The two lovers realise that their cause is hopeless and Nanki-Poo declares that he will kill himself immediately. Meanwhile, Ko-Ko has received a letter from the Mikado, threatening serious repercussions for the town and the Lord High Executioner if an execution does not take place within a month. On seeing Nanki-Poo about to ‘terminate an unendurable existence’, Ko-Ko offers to do the job for him. Nanki-Poo agrees, on the condition that he can marry Yum-Yum and enjoy one month of married life before he is beheaded. Ko-Ko will then be free to marry the widowed Yum-Yum. All rejoice at this resolution, but the festivities are rudely interrupted by the arrival of Katisha. Furious at Nanki-Poo’s rejection she attempts to reveal his true identity. She is silenced by the crowd, but vows revenge.
Act II
Yum-Yum is happily preparing for her wedding until she is informed by Ko-Ko that, under the Mikado’s law, the widow of a beheaded man must be buried alive. To spare Yum-Yum this grim fate, Nanki-Poo again decides to kill himself, leaving Ko-Ko again without the requisite head to lop off. At the news of Mikado’s imminent arrival Ko-Ko sends the young things off to be married while he and Pooh-Bah draw up an affidavit that Nanki-Poo’s execution has taken place.
The Mikado arrives with Katisha and is very pleased to hear that an execution has taken place until he learns that the victim unfortunately was his own son. As punishment, Ko-Ko and his accomplices are scheduled to die after luncheon. Their only hope is to admit the falsehood of the affidavit and produce Nanki-Poo alive and well. But Nanki-Poo, now married to Yum-Yum, is afraid to face Katisha’s wrath so Ko-Ko is left with no other choice but to woo, win, and wed Katisha himself and have her intercede with the Mikado. While Katisha is at first reluctant, being in mourning for Nanki-Poo, Ko-Ko eventually wins her over with flattery and schmaltz.
Back from the dead, Nanki-Poo presents himself and his new bride to his father. Ko-Ko devises an explanation for his subterfuge that satisfies the Mikado, who commutes his death sentence to a life sentence with Katisha. All ends with a joyous song and a merry dance.