>>3207880It's not that weird. Many Japanese really stand on the honorifics. Koone is Marine's senpai and so she calls her senpai. That's all there is to it.
If one of them specifically says something like, "Hey, we've known each other for a while, why don't you drop the -senpai?" then it might change. But it's not a rule of Japanese culture that you
always drop honorifics once you're closer, it's more like it's up to individual discretion.
