I guess I should trust my IME pad a bit more... It was showing it the whole time.
I've seen it in hand-written (usually informal) texts (the 門-part). As a specific example, Yukari from Azumanga Daioh uses it when she's writing down her summer plans.
Krugger said: Is this the cover page of a doujin or a stand alone either case i like art and the concept
The response is a little late, sorry, but here's the source. It's a Suika anthrology, and the artist contributed a short to the doujin (Reisen x Suika), which has a lot of futa in it . http://www.mediafire.com/?m3mjwujzmkt