>>698658Often referred to as hammerspace, it was popularized by Ranma 1/2 as another dimension in which large objects could be stored. Sometimes these objects can display unusual physical properties, so they might be created in this other dimension, and not bound by normal physical laws.
The entry point for this dimension could be a two-dimensional hole in space carried somewhere on a person. In this case, she keeps it between her boobs. The opening may be stretchable for large objects, or the objects themselves might be elastic and bounce back to size as they pass through.
Hammerspace was also used extensively by Bugs Bunny before anime picked it up.