I know that the author is also a fan of American comics, especially Spiderman. In fact last episode when you mentioned Midoriya swinging around like Spiderman I couldn't help but laugh because Midoriya's newest quirk Danger Sense is also alot like Spider Sense. But the reason I mention the American comics is that Tarturus is very similar to a prison in DC comics called The Slab, it's an artifical island that holds meta humans under the water. I wonder if it inspired Tarturus. Speaking of American comics believe it or not Stan Lee actually teamed with a manga artist and worked on a manga for Jump.