Not to mention the existence of hentai, yuri, and ecchi. All of which don't really have widespread western equivalents, despite western cartoons being fairly popular.
Hentai etc are descendants of shunga pics; you've probably seen Hokusai's "The Great Wave Off Kanagawa". You may have seen "The Dream of The Fishermans Wife" (NSFW)
Or so I've read. I'm not really a historian.
United Nations data show that Japan is still, in fact, the world’s largest producer and consumer of child pornography. Its usage is widespread, with as many as one in 10 men admitting they’ve watched it or that they own it, according to the book Sexnomics, by economist Takashi Kadokura.
Almost 80 percent of the child pornography transferred over the Internet is said to come through Japan. According to Interpol, Japanese “entrepreneurs” at home and abroad are also major producers of child pornography in the world market.
Crappy journalism in my view not to mention that the statistic you use is from a different century.