Every drama Seo Yea Ji's in presents her as the most beautiful woman that ever walked this earth and I can't even argue. She deserves all the dramatic slow-motion close-ups. She had much more chemistry with Lee Sang Yeob. And I wanted more screen time for So Hee Jung, she got so little to do here, almost no lines and I always enjoy seeing her.
If it's 18+ rating... Could it be another QUEEN WOO style... Dayum! Now that's drama!!! I'll 'plan to watch'
Depends on the actors. I wasn't familiar with Go Ah Ra and I watched two dramas ''Hwarang'' and ''Do Do Sol Sol La La Sol'' she didn't move during kissing scenes, her co-stars carried the chemistry. Good thing is that this drama has great female director and some people say Go Ah Ra's acting improved since then. We'll see.
It's complicated. Kim Hye Soo and Jo Jin Woong characters like each other, but the way the story jumps back and forth between the past and the present and things changing they never get to have real relationship.
The best shows and films that I watched have low ratings on this site. And most of them are mini series, less than 16 episodes. Reading some reviews people are very harsh towards shows that are not made for TV, like "So sad it's a web drama and not a k-drama". And they skip it without watching and give it low rating. Web drama and k-drama is not the same thing? Aren't they both made in Korea? I had no idea. The quality is the same. Actors don't separate web dramas from TV. Good material is good material no matter what platform it released on. And I know that series that go to streaming service have more freedom with what they can show, with no censorship, better writing and acting, while TV can't show things like swearing or love scenes. Viu, Viki, TVing, KakaoTV produced a lot of great shows. I never trust reviews that put down something based on its lenght or where it released.
My guess they will have some insignificant age difference, one-three years. And even if it's bigger they will be great. These two are the reason I'm exited for this show.
It's very common in films, younger actors play older siblings or parents and other way around. There are many examples. Angelina Jolie played Colin Farrell's mother in Alexander and she's only one year older than him. Stockard Channing was 34 when she played a high school student in Grease. Dustin Hoffman was almost 31 when he played a 21-year old student in Graduate.
Celebrity 
https://www.instagram.com/p/DAqyOQ7y_9W/?igsh=aXVvZTQweXozaDE5
https://youtu.be/-3pYyG80vEE?si=lhAYI21swS-zAmA4
https://jimff.org/w8_3/161
https://m.entertain.naver.com/article/119/0002871130
And the family tree in the photo section - https://kisskh.at/photos/dbKvD_3
https://namu.wiki/w/%EC%B6%98%ED%99%94%EC%97%B0%EC%95%A0%EB%8B%B4(%EB%93%9C%EB%9D%BC%EB%A7%88)
It's very common in films, younger actors play older siblings or parents and other way around. There are many examples. Angelina Jolie played Colin Farrell's mother in Alexander and she's only one year older than him. Stockard Channing was 34 when she played a high school student in Grease. Dustin Hoffman was almost 31 when he played a 21-year old student in Graduate.