The King: Eternal Monarch (2020)

Set across two parallel worlds, the series follows Emperor Lee Gon of the Kingdom of Corea, who discovers access to an alternate reality after crossing a mythical, magical door opened by his treacherous half-uncle, Lee Lim. In this alternate reality—the Republic of Korea—Lee Gon encounters a fierce, justice-seeking detective, Jeong Tae-eul. To save both of their worlds from collapsing, they must work together to retrieve the scattered halves of a legendary flute and stop Lee Lim's atrocities.