Playing Tricks on the Mortal World: I’m a God in Seoul

[Primarily set in modern Korea: A god awakens in Seoul, dominates all, and lives off women]

[The Ming dynasty as a secondary historical setting: The story of an emperor of the Ming Empire and his hapless son from Joseon]

The protagonist manipulates the Koreans and Japanese into fighting each other, while ruling Korea with an iron fist.

Dual-world instances: taking Koreans back to World War II to fight the Japanese, returning to the Ming dynasty to fight the Japanese, and more.

In short, beat up the Japanese.