From PMiSS:
(Because of 洞 in the title and the Sanae screenshot)
>Rumors say that within (youkai) mountain exists a large hollow cavity where a futuristic utopia just like the outside world is being built. Within this hollow cavity, the forbidden act of opening a hole that connects to the outside world through the boundary is perpetrated, so other youkai and humans are not allowed to enter. At least, that is what they say...
(Because of 虹龍)
>It is thanks to the Dragon (龍) that the rain falls, the rivers flow and everything is enveloped in a verdant green. It seldom appears, only revealing itself in Gensokyo's greatest times of need, blocking out the sky. Rainbows and rivers manifest in its wake as proof of its existence.