Recommendations

In both the movies the male leads are ordered to kill a woman by their boss, but they're unable to do so and so they do what they can to protect the woman.

FLU and TRAIN TO BUSAN revolve about the spread of infection.
Both having a child as a cast, making both films..should I say dramatic? Yeah, dramatic, full of emotions actually.
Ma Dong Seok is in both films, playing antagonist on THE FLU and a real hero in TRAIN TO BUSAN. You'll surely get to hate and love this man!
The finale of both films are really similar to each other. (Don't want to spoil.)

Both are supernatural dramas that feature a lively dead girl and a male lead who can see ghosts and their fun and (of course) dramatic romance. I know some people avoid historical dramas as a rule, but Arang and the Magistrate is too fun to pass up and is something even those who swear against historical dramas can enjoy.

Both have a perfect balance of drama and comedy and keep you entertained for the whole ride.

both has a similar story with a poor girl completing tasks in order to earn money by living under the same roof as a group of brothers who are potential heirs of a rich man. Even the first task of making all of the brothers/cousins to eat together as a family is similar. Both has the girl having a mysterious background which will be revealed towards the end of the drama. The Korean version is more drama with some comedy while the Japanese version is more comedy than drama.

The plots are quite interrelated and you will surely cry in this one as well.

Quirky characters, creepy cases, similar off-beat and dark atmosphere. Both also have male x female duo with great chemistry

They both give off a similar feeling. I find resemblances between ji woon and hanazawa rui, but also between hyun min and domyouji. The storyline is somewhat similar as well.

They both give off a terribly similar feeling! Not only the characters, but also the story line so far.

Both have their marriage arranged by their grandfathers, he is rich and famous and She is just a commoner.

Both deal with social issues in contemporary Japan, especially on the breakdown of family due to inter-generational conflict.

brothers fighting each other to become the next Crown Prince...
male leads falling for the "odd yet charming" female lead...
Wang So in both dramas are excellent fighters and were raised apart from the rest of the "family"...

The two are similar in their consistent intensity, action, and impossible situations. Doctor Stranger is also nother Lee Jong Suk starring drama, and is also a medical drama, though the medical aspect is much more prevalent than in W.

Both are about a South Korean man and North Korean woman falling in love. Blow breeze is different in that the man is a lawyer and the woman defects from North Korea as a pose to Han Ji Won's character who was a soldier in South Korea on a joint mission and ends up falling in love with the then prince and who eventually becomes king.

It's my second recommendation for Age of Youth as I was literally amazed, felt so good watching it.

Both have super awesome Soundtracks ( with foriegn songs).
Both have amazing performances from the actors and actress.

The storyline from both drama evolve friendship, romance mixed with some good comedy. Aside from that they are unique and different from each other in term of overall plot.

Both of these Masterpieces gets 10/10 from me. (Gladly)

Enjoy your watch :)

Both female lead roles disguises herself as a man in a historical period.