for those that don't get it, in Japan, you don't actually clean yourself in the bath/onsen, you clean yourself in the building bathing area in the front of the bath/onsen. Kongou is being English and bathing in the bath/onsen which is incredibly disrespectful to others in the bath/onsen.
That's like one of the episode in Therma Romae when the Goth(?) mercenaries enter the Roman bath before cleaning themselves and even wash their dirty clothes in it.
for those that don't get it, in Japan, you don't actually clean yourself in the bath/onsen, you clean yourself in the building bathing area in the front of the bath/onsen. Kongou is being English and bathing in the bath/onsen which is incredibly disrespectful to others in the bath/onsen.
You still bathe, you just don't wash in the bath where all the dirt will wash off into the water that everyone else is trying to use.
That's another layer to this. I'm not sure if it's like this in England, but as someone from America I've only heard words like "bath" or "bathing" in the context of cleaning oneself. The idea of bathing for leisure is unheard of, or at least not associated with the word "bath"; we have spas, but that's treated as an entirely different thing from "bathing"