Recommendations

Thrilling events happen in a villa, somewhere on top of a mountain or in the depth of a forest, where many isolated people there face their death because of some intruders.

Both dramas deal about prosecutors, family murder and in both dramas the main leads try to find out what truly happened that lead them to be in the current situation.

both drama and movie deals about romance that started in an unusual way and both deals with finding your dream

Because of you features the embroidery business, where Her Legend is the fine art of Hand Bags. A cruel relative switches places with female lead when she is to be adopted by a generous and kind woman. Female lead's talent, and positivity help her to rise up in her designs for bags but also to find the lady who was to be her adoptive mother.

This drama is also about bodyguards, with an action, romance, and thriller tag and feel to it. Personally from the trailer itself I think it gives off a funny vibe too. And it also has 16 episodes just like SWDBS :)

Although there is no BL in this drama, it has a strong bromance.

Both dramas have a mean cold-hearted lead male character in the beginning. Also, there seems to be a concept similarity in two of the main leads being in the wrong relationships in both "She Was Pretty" and "Itazura na Kiss".

Both are historical dramas that deal with a 2nd born son who tries to avenge and find his family. Both have a fun and strong (although in Princess Man stronger) love interest.

Both involve MULTIPLE RELATIONSHIPS, psychology and comedy-darkness blend.

In KMHM there's 7 characters/7 relationships due to male leads multiple personality disorder; meanwhile in Love Shuffle there's several different relationships due to a group of people deciding to "shuffle"/swap relationship partners with each other multiple times, to test if there exists such a thing as "soulmate"/one person that's better for you.

While both have multiple relationships, both also have a couple of rootable MAIN couples/OTPs with a good romance arc; making shipping easier, while keeping the complexity of the relationship/s and story in tact!

Recommended for fans of psychology, drama-comedy combo, deep and complex characters and story and believable OTP/romance.

Both high quality dramas that deserve a better rating on MDL.

Multiple people involved in a relationship with one person...:

In KMHN 7 personalities/characters due to multiple personality disorder, played by one actor; meanwhile in TBI 21 actors playing one and the same character!

Oh, and both have one actor in common: Park Seo Joon.
In KMHM he plays the 2nd lead character, in TBI he is one of the 21 actor/actresses who plays the male lead character.

Psychology and mystery. Both involve the complex relationship between a psychiatrist and their client. There is a twist at the end of both.

KMHM is a korean drama, while TGH is a chinese film.

Warning: not much/no romance in The Great Hypnotist. Watch it for the psychology and mystery.

Mystery and multiple people involved. In Kill Me Heal Me, these people are the various personalities of the male lead who has mutiple personality disorder; in Mysterious Summer the mysteries surround different people as it is an anthology series with different leads each ep.

KMHM is a korean drama, while MS a chinese drama. Recommeded chinese drama for people who don't even normally like chinese dramas (I'm one of those people)!

Recommended for fans of original mysteries / not just an ordinary detective story!

Psychology and mystery themed fiction. Both play on the mystery relationship between the leads.

Green Tea is more conversational/dialogue-based, less happens; KMHM has a bigger journey/more happens...but regardless both give their take on psychology.
Green Tea is a chinese film, while Kill Me Heal Me is a korean drama.

There's more similarities between these two besides the very similar poster (lol)...
Both mystery romances, with a chaebol/luxurious life backdrop. The male lead in KMHM must hide his multiple identity disorder from the rich, while the female lead in Mask must hide her true identy as a poor woman from the rich.
Similiar melodrama vibes

Both dramas are about a group of people getting a letter accusing them of having been a part of a murder/suicide which causes them to try and find out who truly killed the person/why the person committed suicide.