When Kim Soo Hyun was asked why he joined the cast, he replied, ŌĆ£I loved the original work. It was very powerful and inspiring. After watching the British and American adaptations, I was curious to see the role (Hyun Soo) in my own version. I thought it was a great experience to reinterpret the role in a more personal way.ŌĆØ
Then he explained the key aspect of his character, saying, ŌĆ£As I was playing Hyun Soo, I have never been this innocent, hurt or heartbroken in my life. Even considering that itŌĆÖs my first thriller series, IŌĆÖve never felt this betrayed before,ŌĆØ with a hearty laugh. ┬Ā Source (1)