Considering Kim Go Eun was the first name announced, she is most likely the first female lead. Second co-lead would be Nam Ji Hyun. Third person in terms of importance would be Wi Ha Joon (as the main male lead). Fourth person in importance is most likely the third and final sister. I am excited by the combo of actors here! All great talents, and all around the same age too!
For me, what’s more exciting is the PD/writer duo. I thought Vincenzo was well directed in scope/scale, while balancing out a lot of characters (which it seems this will juggle 3-4 titular mains), and a slew of others (the sisters will have to fight Korea’s most influential family, which I think WHJ might be a apart of?). The writer wrote some amazing Park Chan Wook films, but Mother is a masterpiece! Please watch it, that was also a women led story (the ML there was more of a supporting character, which could be the case here). This combo, this cast, tvN + Studio Dragon, and the original source material = must watch/possible contender for best show of 22′!!