The fifth video hasn't come out yet. It is allegedly coming out October 31 (the videos are usually released on Halloween). Because this is an independent animator, it takes about 2 years for him to come out with a new episode (imagine waiting two years after the end of Hellbent!) Still, it's amazing how much the animation improves with each episode! I did a little more research, and the back story between Shiromori and Mystery is that, as a a kitsune, Mystery created Shiromori with his blood, which is why she seeks his blood to sustain her. Vivi's ancestor battled Shiromori, and freed Mystery from Shiromri's influence, but he still feels responsible for her. The green hand that grabs Mystery's heart at the end is the same spirit that possessed Arthur. Oh, and Hellbent, is still my favorite, both song and video. Thanks for reacting!

I have a feeling that at least Shiromori and Lewis will use themselves as seals for "Envy" (the green spirit).

Both songs/ videos were incredible."