Recommandations

both dramas are kinda the exact opposite but the same? in FCJMA we have a commoner about to get married only to be taken away and announced as the king, while in 1DMP we had a king/prince who forgot he was a king/prince and ended up "getting married" to a commoner ;)

Both are about a young child who have an incurable disease that exist in the real world. Oh My Geum Bi is about an 8 year old who was diagnosed with Niemann-Pick Disease Type C which has been nicknamed childhood Alzheimer disease. Geum Bi is that 8 year old child and does her best to exercise her mind to keep the inevitable from happening... she is told because of her disease she will eventually wont be able to remember anything and will no longer be able to walk or take care of herself at all just like with an actual Alzheimer patient. To make matters worse, because of the disease her auntie that had been raising her couldn't handle raising such a sick kid and decides to abandon her one day and only gave her information about her biological dad and to go find him to have him raise her. But that biological dad is a criminal scammer who ends up arrested... can this man clean up his life and take the responsibility of properly raising his child? What will he do when he finds out about her disease? That's where this story begins.
It sounds fairly similar to the theme of this drama and so if you like one, you will probably enjoy the other. I personally loved Oh My Geum Bi because of many things but mostly I was glad to know that this disease exists!

Both movies have a strong female lead who is good at beating/killing people and has a mysterious past.

Both women have a hobby of peeping as a sexual fetish and both drama series are adapted from manga series.

Both detective series.
Both male leads are good at their job
The female rookie helping the male lead (also the same actress playing her)

Both are high school horror movies that deal with the supernatural. M.Boy is much darker though, as it gives a realistic take on violent bullying.

Both movies are about students that are severely bullied, bringing them to their breaking points. There's gore in them both and they have creepy tones.

The plots are both centered on odd and quiet high school boys. They both have eerie tones to them, but M. Boy is more gore horror, SCW is more realitistic and dark.

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 both about someone who is looking for a beloved someone they love who suddenly went missing.

Both shows have almost the same MCs, and they both aim to introduce the cultures of different countries around the world. While Abnormal Summit discusses the cultural differences between those countries, Where Is My Friend's Home pays these countries a visit to personally discover their cultures.

Both are about a cop who chases a psychopathic serial killer just after seeing someone they care about violently murdered.

Both are about men who turn into "monsters" trying to get revenge after seeing someone they know being violently murdered.

Each of the dramas describes a forbidden love story between two people that are not supposed to fall for each other.

They are both about a forbidden love story of a man who fall in love with two sisters. While 'Which Star Did You Came From?' is a light-hearted drama, 'Snowman' is more tragic.