I honestly don't know WHAT it is, nor do I care. All I heard when I learned about that site is that it supposedly is a major CP host, so I just avoided it like the plague. Plus it's all in Japanese anyways.
I thought drawn child pornography was legal in more places but apparently its only about 8 counties. Bafflingly this isn't one of the things the EU has a united front on. Funnily there are a lot more countries that ban all pornography than there are countries that allow some porn but not fictional child porn.