According to the RT documentary "Substitutes," industry insiders say that around 2,000 life-like sex dolls - with adjustable fingers, removable head and customizable genitals are sold annually in Japan. Assuming costs come down and the Japanese workforce continues to put in 14-hour days, there could be tens of thousands of sex dolls floating around the island nation within a decade. Maybe don't look in random closets when visiting friends in Japan. 

For sex doll salesman Noburu Tanaka, the advantage of owning one of the ¥420,000 ($3,750) synthetic dolls is its lack of expectation. "It's an amazing feeling. It looks like a doll, but you feel as though it's really alive," he told RT. "When you make love to your wife, there can be some problems. With a doll, none of that matters."