If you did not know already, Catherine is not a game for the youngins. But if you didn't the ESRB has just released information on why this game recieved a Mature rating.
According to the release, Catherine contains "topless female demons", a "colorful demon bride", and "chainsaw wielding babies". However, aside from that there's the usual blood, partial nudity, sexual themes, and strong language as well as use of alcohol and violence.
Some of the 'dirty' lines include, "I finally became a man! Got rid of my V-card, BOOM" and "I've got such a hunger for these feelings. I know you have some hungers as well, don't you?"
So, word of advice, keep this game away from the kiddos, but for everyone else in the US, expect Catherine some time in July. No word on a UK release yet.