Was wondering who Monika really is, *Spoiler*

someone sings at some endings in the game. This person clearly has alot in common with Monika and I was wondering if anyone had some idea as to who she is. There isn't really anything on this wiki to help me, just character names.

If someone could reply and help me that would help me out a ton, was just curious as to who Monika is based on or at least the idea behind her.