Should I use this song as a character song or as my opening? (Song link)?

Starting a fanime...Metamorphose by Asriel is the song. It fits so well with the character, but it is amazing as the opening...Maybe the character theme, because it's also the opening of another anime...But, it's...egh. I can't decide. Please help. http://www.youtube.com/watch?v=Ky4jRtOni8U