Capital Scandal (2007)

Both dramas are dealing with the same time period (1930s) in time of Japanese occupation in Korea, and have very similar theme. Secret group fighting for the freedom of it's people, country and love. I highly recommend it :)

both was based on novel, written by the same novelist, Lee Sun Mi.

the hero in both series act like a traitor and both stories are about fighting agains Japanese but with different background (Korean and Chinese).

The dramas have the same writer. They involve books and the Japanese occupation of Korea...

It is another period piece (although much more modern than Hong Gil Dong) that was written by the amazing Hong sisters. The lead actor is also the same as in Hong Gil Dong: Kang Ji Hwan.