Ok here is my theory about Hwan. In the scene where Chiwoo was supposed to move Hwan was very sad and said that he wishes that Chiwoo would live with him. What if Hwan made a wish as a child that Chiwoo and him can live together and that caused the bridge to collapse and kill Chiwoos parents. He also is indirectly responsible for the car accident that Chiwoos uncle got killed in so that he would have no relatives that he could live with. I don't believe it was his intention to kill Chiwoos whole family but he indirectly is responsible for it because of his wish...
Ok here is my theory about Hwan. In the scene where Chiwoo was supposed to move Hwan was very sad and said that he wishes that Chiwoo would live with him. What if Hwan made a wish as a child that Chiwoo and him can live together and that caused the bridge to collapse and kill Chiwoos parents. He also is indirectly responsible for the car accident that Chiwoos uncle got killed in so that he would have no relatives that he could live with. I don't believe it was his intention to kill Chiwoos whole family but he indirectly is responsible for it because of his wish...