from Beyond the Camera len's translations: http://www.cameraslens.com/index.php?subaction=showfull&id=1213096669&archive=&start_from=&ucat=2&
We can get a few things 1: That the protagonist has ties to a hospital, does this mean the girls pictured on the official site are her and other patients?, or did they all live on this island the hospital has connections to? They were "rescued", but are now dying off. is this a ring style curse?, or perhaps the purpose they were born for, are they more rope shrine maidens or something more sinister. 5 for the 5 elements in japanese folklore?.
Who knows, but the reading makes interesting food for though doesn't it?
What about the name of the game? "The Mask of the Lunar Eclipse"?
what significance does that bear?
The only reference i could find to an eclipse was the Shinto sun goddess "Amarterasu ", Who caused an eclipse by sealing a cave, from what ive read ,hurriedly, on the subject the world was saved by a sumo. which, whilst saying something for the bravery of the sumo, doesn't seem in keeping with the theme of the series.
What about masks?
The first thing that comes to mind are Japanese Noh Theatre masks. The noh performances are based on 6 groupings, possibly it could be used for 5 girls and an eclipse as the 6th grouping?
Although, the Noh theatre has routes in Buddhism, not shinto like i think the rest of the series is, so again. not in keeping with the vibe of its predecessors.
Honestly i dont think ill ever guess the story before i play it, but its fun to think about it and take wild guesses, and learn some folklore in the process.