The Age of Shadows (2016)

- both take place during japanese occupation
- involves spies and betrayal
- action-based with suspense
- both with a very strong main cast

Although set in different centuries, one is in the Joseon era and the other is in the 20th century, both are about Koreans defending their country against the Japanese invasion.

They are historical shows about people who fought for the Korean independence during the XXth century. Espionage, patriotism and politics.

Both dramas deal about a group of people that tries to fight for koreas sovereignty. Both are quite powerful when it comes to father land, fighting for what one believes to be right and international relations.
Both dramas have well thought through stories with people that jump between the sides. Also both have quite interesting spies.