In KWOW episode 107, we learned about the music scene in Korea that existed before Kpop: pansori. To say pansori is the Korean version of opera is not completely accurate. It's the traditional storytelling told in musical form, performed by one singer and one drummer.
Listen to some pansori performances with subtitles in many languages:
What’s the difference between pansori and Western music? How different do pansori singers’ vocal cords look compared to Kpop singers? How are people modernizing pansori these days?
Pansori Masters' Battle!