When entrepreneur Lee Hee-tae told his parents he was going into the porn business, he urged them not to worry about social disapproval in conservative South Korea and to think about the money instead.

The financial case, he said, was clear: built-in domestic demand plus a growing global fascination with South Korea, thanks to booming K-pop and K-drama exports.

However, due to deeply conservative social mores, South Korea's adult industry is a minnow compared to neighboring Japan.