They are not separated by being Japanese or not, but ARE by having an individual thread for every game that makes the cut. I did not say there was both a separation and not a separation, what I said was there was not a spearation by one aspect, but by the fact that no game gets put into the same thread as other games without being part of a collection thread, which are specifically designed around being collections of that particular dev's work.
As for turning what you don't want off, I do believe you have to actually go to that tag's page and hit ignore on that to not see it. If a game is Japanese, it will have the "Japanese Game" tag. Most games are going to be animated in some way with the most used style being the typical anime art style or the Illusion 3D or anime art styles. Only the really lazy or incapable devs, and for the record there is nothing wrong with not being capable of making art for one's game, will use real pictures, which are basically the only alternative that includes pictures, in which case you could filter the tags to include only games with the "Real Porn" tag in the box on the right in latest updates.