Episode 8 is a tearjerker. I can't wait for Tes' true identity to be revealed.
Tes was the doctor who possesses Cha Young Min when he was a first year. And Tes and Seung Tak's grandfather were friends. I think Seung Tak's grandfather also can see ghosts that's why he knew that Tes is still there at the hospital. And Seung Tak inherited that power from his grandfather.