For Some Uncleared Question On The Story?

Why Byul Or Han Jung Yeon (The Alien Whove Been Created The Memory Cube Of Woo Jin) Came To Earth Since 2008?What Is Her Intention To Invade The Earth?

Her reasons were unstated in the drama, although personally, I don't think she came to Earth to invade it. This is probably a topic that would've been touched upon if Circle had more episodes than 12. The writers decided to focus on the subject of "memories" and create a cliffhanger for the whole alien plot to acknowledge its existence for us the audience, but at the same time, say that don't really have enough time to create a subplot. I'm pretty sure this would have been a subject for a non-existent Season 2. :D