4. The World of Married

5.Red Wine in the Dark Night

7. Flavour It's Yours

8. Plus & Minus

9. Now, We Are Breaking Up

10. My Sassy Psychic

Someone mind to started the next topic? I have no idea to continue the next one XP

10 dramas where people are trapped in a hotel/building/island/palace etc   basically  are isolated and can't escape and there is a serial killer who starts to kill all people one after another and then people number start to decrease and victims' number continue to increase and people start to suspect each other for example  Remember 15 (2022)

2.  Soshite Daremo Inakunatta (2017) - based on Agatha Christie's And Then There Were None.

This topic is very specific - I don't think you'll find more than a few because there isn't much demand for this type of plot. I can think of some dramas where people who belong to a group or a family realize that they are being killed, but they aren't trapped. Also, usually it's not a serial killer if there is a reason for the murders (revenge, inheritance, etc.).

3. Me and Mr. X Season 3: Goodbye Mr. X

* Not sure if you want to count it though, it mostly fits but there is no serial killer per se. It is an organization I believe, unless they did get one of the characters to kill the others, and I just don't remember. I also can't remember if they ever started to suspect one another.

4. Ju-On : Noroi no le(2020) - Not exactly what you are looking for, its kinda reverse, like the people who go inside the specific house ends up dying at a point.

*There are many movies(western) for this topic.

maidenholmes yes, it is really tough to find these sorts of dramas but yeah, I am completely fine if there is no serial killer but it happens for revenge etc 

NoirRoseHeart yes I think so because like maidenholmes  said this type of plot is not in demand so it will be tough to complete 10 names I guess as DavisLoret  said this type of thing is more  in western

5. The Stranded - I haven't watched this one yet, so I can't be sure, but from the description and the trailer, this seems to fit. 

(By the way, if you decide to watch this, don't expect a second season, at least, not with the same actors because one of the main leads died).

I guess the topic is stalled someone can start new topic thank you

10 Drama/ Movies which has more than 2 Second lead couple excluding the main leads (try to post a pic)