The similarities between this episode's killer and victim, and the two main protagonists of
MariMite, is pretty remarkable:
In both cases, you have an all-girls school with a certain air of refinement to it. In both cases, you have a taller, respected, older, smooth-talking, long-dark-haired beauty. In both cases, you have a shorter, charming, twin-tails girl that looks up to and admires her.
At least somebody on the Psycho-Pass Production committee was
clearly influenced by MariMite, and decided to darkly invert it. As a big fan of MariMite, I found this quite chilling and effective.
What I think Gen is good at is taking these almost iconic images that anime fans tend to have warm mental associations with (these yuri/shoujo-ai archetypes, magical girl aesthetics, etc...) and showing how you can have this same imagery but with a much darker reality behind it.
It's very effective. It would be kind of like a comic book where the lead villain has the same appearance, mannerisms, style, and strengths of Superman, but is a brutal killer. Not Bizarro Superman, but something much more disturbing than that because the visual similarity is greater.