ended up rereading the whole arc after seeing the final cosplay, just to really absorb all the details that went into it, like how Gojo was imagining Marin while talking about how to design the cosplay, so when he gives her direction on how to act she's hesitant but he doesn't let her even begin to doubt herself, because he's pictured in his mind from the very start how she would look in this cosplay, it's literally built for her and he can see exactly how she would look before they even start
there's a bunch of other little things like that, I love that both Gojo and Marin take a deep breath before going into serious mode (huu... suu...)
the best bit was mentioned early on that in the Mandate From Heaven manga, Haniel only ever looks directly at the reader, so when Marin switches into serious mode this chapter she's looking directly at you