W

W and Nine are written by the same writer, Song Jae-jung, in which she managed to establish unique concepts in creating the world of both dramas. Even though W has only aired two episodes, it delivered a very intriguing and interesting story just like Nine. The two dramas have different plot (Nine is a time travel themed while W revolves in the fictional world of a comic character) but I must say, they actually resembles each other in the way that suspense, humor, and romance has a nice balance on the way the writer tells the story while still focusing on the fantasy element of the drama.

I don't know why but for me they seemed similar, I think it was the "supernatural/fantasy" aspect, if you liked Abyss I'm sure you'll like W too.

Female lead travels inside a fictional world in both dramas and find love.While world in W is set in the comic book, Unique lady goes inside a game world.

Both female leads look alike and are strong and decidide,the 2 dramas are about parallel universes and they are really good romantic stories .

Both dramas have crossworlds travel between the world of an action novel/manga with a suffering protagonist fated to be killed, and the real world of the writer.

Both are dramas in which the MLs are from a comic book and the FLs are from the real world, and the two meet when one crosses over to the other's world.

They have a very similar feel. Both are dramas with unpredictable stories, dark plot, mysterious antagonists and plot twists.

In both the ML (played by Lee Jong Suk) is falsely accused of a crime that he didn't do and he tries to prove his innocence by exposing the real villain.

Both of the stories are really unpredictable. W and Liar Game (Korean Remake) Keep you hanging, although W has 16 episodes and Liar game has 12 episodes.. which is really sad because I wished it was longer...

Ambos envolvem sonhos/outro mundo. Achei incrível a temática e achei similar principalmente pelos desenhos e todas os momentos envolvendo webtoon

Crown Prince Yi Gak finds that he has been transported from the Joseon Dynasty to modern-day Seoul. He meets Hong Se Na, who bears a striking resemblance to his dead wife, and is determined to solve the 300-year-old mystery of her death. With his own resemblance to the CEO’s grandson at the company where Se Na works, Gak assumes the identity of the young man to stay close to her. Can the Crown Prince navigate a modern corporation to find clues to his own time period?

both has manga/webtoon which is drawn and kinda comes to life
in the movie it comes true for real in the real life
in W kdrama it first builts the other world where characters appear are developed and slowly from there it begins to actually affect reality

Both about two differents worlds and the female lead moving from her world to another. FL meeting someone who helps her in need and there is a secret about the 2 worlds that the leads are working to solve.

W contains romance, while Derailment is still ongoing drama so I don`t know yet if it has any romance at all.

Both dramas involve characters in the real world existing in a fictional one/a parallel on. Both take place primarily in a comic book/fictional story universe where the female leads know it is fictional and are trying to change end of the story.

Both story where reality and friction get blended. MC can travel between portal to different worlds.

both have a male lead who is not a real human
both have a lot of suspense
both have a love story that people do not approve of