During the climax of Yumi and the Nightmare Painter, we learn that the Father Machine sucked the souls out of nearly every human being on the planet. Yet, we also see that the only thing the machine is capable of doing is stacking rocks, as well as imparting a little bit of Intent as it does so. This means that, so long as one is good enough at stacking rocks, they can rip the soul out of a person. Not only that, but the Father Machine was able to steal and lock up every Spirit on the planet just by continually stacking rocks.

Yumi is shown to be explicitly better at stacking rocks than the Father Machine, and has the capacity for far more Intent and willpower.

Yumi can easily steal the soul of every person on the planet if she so wishes.

Yumi could probably reforge Virtuosity in an afternoon if she set her mind to it.