In Chinese the words seperate out as "Sex" "Behavior" or in short SexAct. The process of doing sex. China has tight restrictions on internet activity so often the term is often only found outside of China. This is what I am told from the native speakers on the China boards.
Example
http://blog.roodo.com/gamy543/archi...-12.html&page=5
In Japan "activities" are more often searched by the actual desired result. Ie "Old man young girl" or "pee on me" and the sort.
性行為 meaning Sex in Japanese is a broad category. More accepted by the public and often used for describing terms related to the English word Sexual. Ie Sex therapy. It is though seen as the broad category that represents the actual activities that are involved with sex.
Take for example the Wikipedia page on 性行為
http://ja.wikipedia.org/wiki/Catego...%A1%8C%E7%82%BA
Notice the catagory of 性行為 on the page is used to represent the sub definitions below which include some topics I wont post here because this is not an adult forum.
Searching the image base from Google you will get a reference on the usage of the term. Do turn off the family filter prior to the search
http://images.google.com/images?q=%...F-8&sa=N&tab=wi
I hope this helps to clarify the term. It is information that I obtained from many native speakers. If you know otherwise please do post.
thanks
