Suitengu is actually Sephiroth!Just watch episode 10.
There was no other safe way Saiga could have taken pictures.Even if he'd only looked to line up the shot and looked away or closed his eyes while he took the picture, the subject still would have exploded, because of the weird way those abilities work.
The Euphoria Factor is like a cancer.Sure, they'll get special powers but eventually everyone who has it is gonna die in one way or another. I think was made obvious by Kagura's development.
the Roppongi Club is the same secret society from Eyes Wide Shutcome on, it should seem obvious, a secret society that throws parties where the elite can get their rocks off without having to worry about anyone finding out? perhaps what Tom Cruise encounters in Eyes Wide Shut is the western branch of the the Roppongi Club and assuming that the movie takes place in 1999 and the anime in the near future, perhaps Kagura wasn't born yet
Kazuya Shirogane is somehow related to Voldo from the Soul Cailbur gameesThat or Monkey D Luffy