She is Elmer's Wife, japanese mature woman who gave birth and has her right nipple pierced. She started training by her husband (or so) at least since 2006. Seems like this is a small group of people sharing their wives being fisted and have a website with legitimate representator. So yes, they are serious but I can't understand their motivation as their website is kind of "log in to see everything or stay out". And registering is quite hard with foreign card holders (outside of Japan).