[In all fairness, Asch, you're talking to a spider lady. Unnatural is relative.]

It seems that my world is a bit more used to magic being used casually as part of everyday life than most- though I admit that this particular type of magic is new to me as well.

[She has some suspicions about whatever the fuck it is Sans does, admittedly, but whatever.]

If you mean that it wasn't formed by nature, however, then yes. The Storyteller seems to be responsible for it, as they are for the islands themselves.