Surprisingly, the director allowed a standard definition version of The Five to be hosted on the Internet Archive for educational purposes in 2015. While this version is low quality (360p), it is the only completely legal, free, permanent download available. A simple search for "The Five 2013 Internet Archive" will yield the MP4 file.
Kim Sun-a’s Performance: Known for her versatile acting, Kim Sun-a delivers a raw and haunting performance as Eun-ah. Her transition from a happy mother to a vengeful, broken woman is compelling. the five 2013 download