True I've only seen three (there are eight and this is number six) but this one wins because of Yuma Asami. As others have said, she is gorgeous and I think these kinds of films depend a lot on the leading lady. Also the cinematography is better compared to the other two I watched... that isn't saying much since it still isn't that great but hey this is grading on a curve. Yeah nobody cares about the cinematography... how hot is Yuma Asami? Very hot and the story moves at a decent pace. Can't believe I'm talking about the story in something like this but there is more of a story than say Red Account: My Bloody Angel (1988). True still not much of one and like another reviewer pointed out, they could've done a lot more with the supernatural aspect but still I prefer this over New Siren (aka Siren 5 aka the one from 2004) or Siren XXX: Magic Pleasure (aka Siren 8... the final one).