From the article :

“Increased openness in many countries towards sexual themes may be prompting interest in erotic art. The surprise success of the sensual Fifty Shades of Grey books comes at the same time auction houses are reporting competition for rare and one-of-a-kind items, which change hands for hundreds of thousands of dollars…..

For Uragami, who lent items to London’s British Museum for an exhibition in 2013 to 2014, sharing is key.

“Pornography is something to see by yourself alone but in the Edo period

[1603 to 1868] people went to see shunga together, to discuss and debate and share the happiness of them,” said Uragami. “It’s my pleasure too, to see other people discovering and enjoying shunga.”……

In certain genres of erotic art, dedicated collectors are vying for the few exceptional artifacts to have survived destruction by officials — or inheritors — through the centuries.”

Read more:

http://www.bbc.com/capital/story/20150311-collecting-sex