Music by Arthur Sullivan
Libretto by William Gilbert
First performed on March 14, 1885 at the Savoy Theater in London. The Mikado ran for 672 nights.
Place: Titipu, Japan
Time: Olden times

Act I

The courtyard of Ko-Ko's palace in the town of Titipu.

The Japanese nobles are posing in various poses from Japanese painted screens (If you want to know who we are). A wandering minstrel, Nanki-Poo (in reality the Mikado's son) arrives looking for Yum-Yum, the ward of Ko-Ko (A wandering minstrel I). He has returned to marry Yum-Yum now that he's heard her engagement to Ko-Ko has ended as Ko-Ko is to be executed for flirting (a capital offense). The nobles tell Nanki-Poo that Ko-Ko, a former cheap tailor, was reprieved and made Lord High Executioner.

Pooh-Bah (Lord High Everything Else) tells Nanki-Poo that Yum-Yum and Ko-Ko are going to be married that day. Ko-Ko arrives and tells everyone how he received his position as well as how he is going to deal with society offenders (I've got a little list). Yum-Yum arrives with her two sisters, Peep-Bo and Pitti-Sing, all of whom are wards of Ko-Ko (Three little maids  ). Yum-Yum is not thrilled at the prospect of marrying Ko-Ko but she's resigned to her position until she sees Nanki-Poo. Left alone, Nanki-Poo tells Yum-Yum that he's really the Mikado's son who's running away from court to escape marrying the elderly Katisha. Yum-Yum and Nanki-Poo bemoan Yum-Yum's engagement to Ko-Ko and sing what they might do if she was unattached (I would kiss you fondly).

Ko-Ko has received a letter from the Mikado, who is curious as to why no executions have taken place in Titipu for a year. The Mikado has decreed that someone must be beheaded within one month. The condition of Ko-Ko's reprieve was that he could not behead anyone until he himself was beheaded first. Nanki-Poo reappears with a rope intending to hang himself since he cannot live without Yum-Yum. Ko-Ko persuades Nanki-Poo to become the beheading victim within one month. Nanki-Poo agrees if he can marry Yum-Yum for that one month. Ko-Ko agrees to the marriage taking place the next day. After all, Yum-Yum will become a widow within a month, leaving her free to marry Ko-Ko.

Yum-Yum and Nanki-Poo celebrate their impending wedding, when Katisha appears to claim Nanki-Poo. She is told by Pitti-Sing that he's going to marry Yum-Yum (He's going to marry Yum-Yum). Katisha threatens to tell everyone who Nanki-Poo really is, but she is drowned out by the chorus. She storms off to tell the Mikado that she has found Nanki-Poo.

Act II

Ko-Ko's garden.

Yum-Yum is preparing for her wedding. She and Nanki-Poo are deciding how to spend their month long marriage when Ko-Ko arrives to tell them that he's found a problem. Ko-Ko and Yum-Yum cannot marry since it's the Mikado's law that when a married man is beheaded, his wife must be buried alive. Although Yum-Yum loves Nanki-Poo, she has several problems with any outcome. If she marries Nanki-Poo, she will be buried alive in one month. If she doesn't marry Nanki-Poo, she'll have to marry Ko-Ko then Nanki-Poo will commit suicide and there will be no execution (Here's a howde-do).

Pooh-Bah tells them that the Mikado is coming to town, apparently to see if his execution order has been carried out. Ko-Ko is unprepared to execute anyone, even though Nanki-Poo offers to carry out the bargain immediately. Ko-Ko thinks that all he needs is a death certificate and persuades Pooh-Bah with cash to certify a death certificate without beheading anyone. Pooh-Bah agrees. Nanki-Poo and Yum-Yum are encouraged to get married then run away while the others make their plans to fool the Mikado.

The Mikado appears with Katisha (I'm his daughter in law elect). The Mikado describes his method of punishment (Letting the punishment fit the crime). The Mikado is told that an execution has taken place and is handed a Coroner's death certificate. Ko-Ko, Pooh-Bah and Peep-Bo describe the execution to the Mikado (The criminal cried, as he dropped him down). The Mikado did not come to town to check on the state of executions, but to find his missing son, Nanki-Poo. Ko-Ko tells him that Nanki-Poo has left town, but Katisha sees Nanki-Poo's name on the fake death certificate. She tells the Mikado that Nanki-Poo was beheaded that morning. Ko-Ko, Pooh-Bah and Peep-Bo beg for forgiveness, but the Mikado tells them they will be put to death for killing the heir apparent.

Nanki-Poo returns with his new wife, Yum-Yum and Ko-Ko asks Nanki-Poo to appear to save their lives. Nanki-Poo refuses unless something is done about Katisha. Nanki-Poo convinces Ko-Ko that the best way out of this situation is if Ko-Ko agrees to marry Katisha (The flowers that bloom in the spring). Ko-Ko proposes to Katisha who rejects him at first, but after much persuasion accepts the proposal (There is beauty in the bellow of the blast). Katisha asks the Mikado to show forgiveness on the conspirators including her new husband, Ko-Ko. Nanki-Poo arrives with Yum-Yum and the Mikado accepts their prayers for mercy. Katisha is not happy that she's been deceived by Nanki-Poo, but she is content being the wife of the Lord High Executioner. The town of Titipu celebrates the joys of marriage (Finale  ).