I have a japanese girlfriend and she's everything I've ever wanted in a girl. The other day she told me that when she was young and living in japon, she had a friend who she used to masturbate with, then one day her friend asked if she could masturbate her, my girlfriend agreed, and when she reached her orgasm she returned the favor to her friend. this went on for a while until they ended up giving each other oral sex to orgasm as well, she said it was very pleasurable but never wanted to do it with another girl.