I love Romantically Apocalyptic, can't wait for the next issue! What I like about this one is the thoughtful "look" of Captain and how Snippy seems to be just annoyed, he probably knows that the next idea Captain will have will be simply... "Captain-ish".
i don´t know for sure, it is a kind of waterproof (and in the comic even fireproof XD) outdoor jacket, but it is hard to get, because the exact model of the jacket seems to be out of production. it is very hard(and expensive) to get a similar model. i know because i did a cosplay of this guy.
[link] the jacket was a H2O " Pearl ",2 in 1 Outdoorjacke Damen,black/weiß
it was this shop, but it was the last one, it has been more than 6 months ago and they don´t seem to have more at the moment. perhaps going on ebay or amazon using outdoor jacket black white as keywords helps, thats how i found it. good luck