Index Corporation and Dengeki are putting out a Catherine art book -- a smart move, since the game's art generates more discussion than anything involving actual gameplay. The book's called Catherine Visual & Scenario Collection ♀VENUS☆MODE♂, because why not?
It runs to 160 pages and is split into five chapters -- Visual, Theater, Cast, Nightmare, and Concept. As well as pictures of Catherine dressed up like a nurse so you can do some wanking, the book contains all the game's dialog and multiple endings.
This part of the post would contain more references to masturbation if I could be bothered to write them.
No details yet on a release or potential availability outside of Japan, so stay tuned for that (haha, stay tuned, we're not a radio station, even).