In Japan, there are tons of adult movies based on video games and anime. A good way to judge the popularity of a game or a cartoon is to see if it's inspiring blue movie adaptations.
Is new anime Sword Art Online popular in Japan? Well, as porn star Hibiki Otsuki has revealed, she is starring in an X-rated version of it, slated for next spring... And that's actually a pretty nice outfit.
In case you missed them, here are Kotaku's impressions of Sword Art Online (the anime, not the adult video.)