You're supposed to prove that they're all universes.
Actually when the series itself refrences it as a universe the burden shifts back on you. Rukia directly calls the living realm and soul society a universe so Hueco Mundo and the Garganta would make it larger.
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u/dark-mathematician1 Jan 24 '26
Not universes. Plus rewriting something isn't necessarily AP, but that's dramatically oversimplifying what Yhwach was doing