Ok, I might be tripping but, in page 14 at the third panel behind the speech bubble at the left, isn't that Kaguya shinomiya from Kaguya-Sama wa Kokurasetai? I'm tripping right?
Welcome to Golden Kamuy, where war veterans get drunk mid battle, slap each other's ass and an Ainu Girl beats the shit out of Jack the Ripper. I love this manga.