So, I decided to start doing...way too much research on Gensokyo the other day, and chose to find a place where an entry point might be.
I started by reading about Gensokyo itself, and the point that caught my attention was that Gensokyo was a haunted region of Japan, until it was sealed off. So, naturally, my next thought was to look up haunted places in Japan. I came up with three.
-Amiidaji, the Temple of Amida
-Aokigahara, a large forest at the base of Mt. Fuji
-Okiku's Well (in Himeji Castle)
I stuck with Aokigahara, after reading about it some more.
The place is thought to be haunted by
'yurei', which immediately made me think of
youkai. Another thing about Aokigahara?
It's a popular place for
suicide. Oh, look, Yuyuko Saigyouji (supposedly) committed suicide.
(http://i.imgur.com/oBopvP7.jpg)) Where, you ask?
Under a
tree. The Saigyou Ayakashi, to be specific.
So, I determined that the Forest of Magic and Aokigahara must be connected... somehow. Meaning, if you found the connection and somehow made it to the other side, you'd come out near the bottom of Youkai Mountain, somewhere in the Forest of Magic.