There should be a better way to handle this than just deleting pages like maybe putting up a warning before the page is displayed saying "this page contains nsfw themes do you want to see it?". And while I'm on the complain train "displaying" is incredibly vague. Vocaloid is about music so what counts as "displayed"? Shown in the pv? Mentioned in the lyrics? Alluded to? Venomania shows no intercourse with minors (Miku's character being 18) Fuyou is about murder and not rape. RedWhiteBlack Genealogy shows one shot of the prince grabbing on to Snow White and that's it.
Yeah I have to say that straight up deleting entire pages is a bit to much and besides, removing stuff because they're nsfw have killed websites before *cough*tumblr*cough* and chances are it's not going help this site either.
I think this is great, however perhaps piapro should also be included given how big it is.