Hey, I was playing Project Zero 3 and I think of a NPC for you.
Description:
When you look at the mirror, you saw a strange woman looking right at you. Don't look at her eyes? No. Don't look away from her. Not until she lost her interest to you.
How about this: She is the store owner in your game and you can access to her store through mirror. But don't you dare skip her lines or it will result in a hitten boss fight.
I think you'll want to wait until I unveil the main story before proposing characters like NPCs. Most NPCs are already decided on, including this incarnation of the shopkeeper. But since the story is still not completelly decided, I might open it up for proposals when the time comes.
Also, I must remind that NPCs such as shopkeepers will only come in handy if this turns into a game.
Also....... Isn't this character from Fatal Frame or something like that o.O ?