Both are historical Korean drama involving letters. The beginning of letters, words and books. Great watch.

Both has to do with Korean letters Both went through hardship to preserve the letters and future literatures

Some story, same drama. Chinese one even found female leads that look a little bit like the Korean original one, LOL.

Both are Korean films involved with train skilled agents. Both main leads fell in love and has feeling to each other. If you like action, romance , suspense drama. iris has drama as well as movie

Both movie involve a security agency either government or private, skilled trained organized personal. Mission, action, intense movies

Both are very intense action suspension film. Very obvious villain and good guys. Protect beautiful female lead.

Both are about kidnapping of a weak person. Both involved security agent or agency. Protective action thriller. Fun watch

Name sound alike, both are security or government agency that protect people against foreign bad guys. Both have beautiful main leads. Fun intense watch.

Both movie has to do with telephone call. The call somehow connected two stranger. Story entangled, twist and turn. Kind of unpredictable

The similarity are about a good looking, poor young man and piano. Although they were in different plot, both has beautiful music.

Both are Japanese movies involve piano. Both male main lead play piano. Beautifully filmed. Slow pace. Very artistic

Both are piano movies. I have not actually watch Secret yet but it is on my list. I assume both has beautiful OST and filmed beautifully