Not censored. It's openly discussed in the literature. Unsurprisingly, they don't let you spread unsubstantiated claims about massacres, though.
If, as I've seen many a white "journalist" do, you go up to a random chinese person on the streets and ask "Hey do you know about the thousands of people that were massacred?" they would, very understandably, think you were deranged.
we're just normal men... we're just innocent men