>>16981170I'd bet it's inspired by Queen Gorgo from 300 (pic attached). That film basically gave an entire generation a widely inaccurate idea of what ancient Sparta was like. You can see when the straps are removed and the boobs get anime sized, the inner sideboob energy is off the charts.
Obviously Ancient Greek women (even in Sparta) didn't actually wear these things. A cursory Wikipedia skim suggests a Peplos or Chiton are more historical (and considerably less sexy).