The Mikado

The Mikado, or The Town of Titipu is a two-act operetta. The book and lyrics were written by W. S. Gilbert. The music was written by Arthur Sullivan. The operetta premiered 14 March 1885 at the Savoy Theatre, London, with the D'Oyly Carte Opera Company. 
"The Mikado" is the ninth of the fourteen Gilbert and Sullivan operettas. It had 672 performances in its original run. This was the longest original run of any Gilbert and Sullivan operetta.
At the time of the operetta's creation, London was overwhelmed with all things Japanese: tea shops, kimonos, fans, etc. Gilbert reported that he got the idea for "The Mikado" when a Japanese sword fell from the wall of his study.
Story of the opera.
Nanki Poo is the son of the Mikado. He has disguised himself as a wandering minstrel to be near the village girl he loves Yum Yum. Their love is complicated by an old woman named Katisha who believes she will marry Nanki Poo. In the end, Nanki Poo and Yum Yum are united. Katisha settles for Koko, the town's executioner.