Yep, a good ending would be a challenge to think up. There'd have to be some kind of 'overall plot', perhaps.

Maybe the story could end when Lulu's finally become the person she is in X - dark-clad, emotionally closed - standing on a hilltop, watching the sun set and reflecting on events in her life.
Or something.

I should also add that there'd be interesting potential for back-story details like where and when she studied black magic, and how she learned to use stuffed toys as weapons - something none of her friends understand.