zeamays:
Um. Are you sure either one of these is a real person? "Mi Sang" means "unknown" and gets used often as a placeholder in Korean cast lists. It would be a terrible idea for someone to take on that name as a stage name, haha. The only place I see this listed elsewhere is Hancinema and not on any Korean sites.
Yep
https://ko.wikipedia.org/wiki/%EA%BD%83%ED%8C%8C%EB%8B%B9:_%EC%A1%B0%EC%84%A0%ED%98%BC%EB%8B%B4%EA%B3%B5%EC%9E%91%EC%86%8C
I belive it was taken from hancinema as you said: https://www.hancinema.net/korean_drama_Flower_Crew_2p__Joseon_Marriage_Agency-cast.html but i also thinks, from the context, that some little guy, with uknown name, played child version of main hero brother or it's mistake. They always list roles, from official drama site, so i belive, they credit him, without pic, and that's how the unknow part, was there. Or they mistaken, because when i checked official dramasite
http://tv.jtbc.joins.com/cast/PR10011096/12 nobody match this character description or i'm blind. We have some missed people there (i mean without pic, but i don't see that guy :P)