Gillian Yeoh

I love this drama really but there are a few things I can’t understand: Who is Johan actually? I don’t think he’s just a mere human, what is his history? How did Yeom-Ji get involved in all this? What is her destiny? Why is she chosen by those ppl in white robes? Who are they? And what other more secrets that granny is hiding? Why does she know that Yeom-ji alliance with Gungtan but didn’t say anything? I’ve lots of questions