I absolutly love this movie!!! It’s the best “J-Horror” I have seen and I have seen quite a few (I know it’s not Japanese, but it falls under that familiar title).
If you’re stuck on anything I recomend the IMDb page - I know it’s IMDb, but there was something I found on there that made things a lot clearer after I had seen this movie.
I think this is the link - http://www.imdb.com/title/tt0365376/board/thread/69288079
Movies like this and Ginger Snaps have a special place in my heart (what does it tell you about my heart that I would say this about horror movies) because they involved sisters who are very close. I have such a relationship with my own sister and so I always feel more involved with a movie that shows it and well.
It’s a very well made movie and if you only see one “J-Horror” it should be this one! It’s a bit of a mind f**k too!
FYI the bag in the road thing is some kind of tradition in Korea or so I have read.