I literally made an account just to say this:
This prologue as a story is SO GOOD.
I'm hooked! Despite the short amount of time we spend with her, Kat definitely stands out to me as a protag and quickly establishes herself as a very human character, neither angelic or evil to begin with. Great writing of all the characters, demon and human. Also the art is just gorgeous, pixel and otherwise.
Moreover, theres so much potential in all of this, which in itself is exciting! The quality of the writing so far leads me to believe that you both will make some dark/interesting routes/easter eggs heavily based on player actions, and that is very promising to me.
The only real thing I can criticise is the ending being rather abrupt, though this is understandable as this is only a prologue.
I await patiently (but excitedly) for whatever update there may be in the future. Stay safe and be well.