Ahhh, what is this drama doing to me. I don't think the writer thought deeply about the science behind it either. I believe that there are only two worlds as KC said, Yeon Joo's and the one Kang Chul lived in but the manwha was a portal between the two and KC's manwha world ...
Yeah, I watched this video on Youtube about why Kdramas suddenly fall out of line and become shit mid-way, and one of the main reasons is that they don't film the scenes chronologically. Another contributing factor is that the script-writer doesn't really have a clear-cut mindset on ...