Recommendations

Both deal with two very different people finding a balance with one another. From Five to Nine has more romance though and is centered around young adults rather than teens.

A complicated like-love friendship but Night Flight is much more darker and it differentiates a lot the main characters.

Mothers studying at the same school/college as their childrens...

Both female leads undergo plastic surgery due to money issues and both have a guy friend who realizes their feelings after the female lead leaves.

The korean version remake of the original Jin
same story, same characters

with a mysterious death at the center, leads decide to take their investigating to the internet and what follows is a media firestorm, a whole lot of online witch-hunting, netizen hypocrisy and backpedaling

Both are melodramas about two people with no real kinship that are raised as siblings and fall in love in the path. In both cases, the lovers hide the truth to not hurt their families, except that in "Piano" the protagonists share a sister, causing that society really sees them as part of the same family. Sad endings.

They are both about family, finding love, overcoming obstacles and over bearing in laws

they both share some sort of nostalgia. "Our Times" has a general story plot where the main girl reminisce her past until the end. While "The Way We Were" switches from past to present. Both of them involve the 90's, where the "good girl"hangs with the "bad boy"and falls in love. Then "bad boy" does have a tragedy happen to him.

Both dramas tell the story of four close friends and what it means to live through love, family, success, and failure. I definitely enjoy and would rather watch female empowerment, but GD also had strong male characters and stories.

Both drama are about divorcees ending up with each other. One More Happy Ending has a ton of divorced characters, but in Emergency Couple, I believe it was just the main couple.

I want to avoid sharing too much, so I'll say this:
if you've already seen one, searching for something similar, watch the other

btw, good shows, based off good novels, some good music, not for sweet dreams..

(I think especially if you've found *yourself* in one, you'll like the other)

regardless of the story, the actors found themselves in characters that fit them perfectly; and are good
(Kamiki Ryunosuke, Katori Shingo, Yamapi / the - incidentally all somewhat anti-heroic - Shizukui Kei, Hiratsuka Heihachi, Saionji Kosuke)
and it's pretty much what holds the shows...