Welcome to Sigil, the "City of Doors", a place with gates that lead anywhere in existence, provided you have the proper key. It is a neutral ground and watering hole for races across the multiverse, all under the watchful shadow of the Lady of Pain, the enigmatic ruler of the city. It is a place where the word is mightier than the sword, where thought defines reality, where belief has the power to reshape worlds and change the laws of physics.

Matara Okina - The Lady of Pain in ass Of Gensokyo
That Reimu is no coincidense