So, good timing perhaps? It wasn't released this year, and psychological anythings are few and far between (in this case also mixing hardcore violence, stark nudity, cuteness, love harems, comedy and everything else: in that way it is unique); I'm fascinated by the distribution methods also limiting what is popular too; some series are not released with dubs, or at all, in America or the UK for many months or even years after airing on TV in Japan, that and the way of watching anime legally in the US and UK are pretty limited sadly.

In any case, there's never enough information beyond an indicator that something is just popular (why it is popular can vary beyond it being good; marketing alone accounts for the vast majority of sales of any entertainment media; although perhaps anime has more word of mouth...hmmm). With anime you also get the issue that it isn't widely reviewed (even less so then TV, which has so few critics it is hard to find when a TV show is "critically acclaimed" unless it wins an award).

Still fascinating; top 5 for so long and that.