According to a comic and some historical research done by the tumblrite betasuppe, there's actually every chance that coffee's been introduced to Hisui, but, in their words, "didn’t catch on since it tasted so bitter." Checking with the Ginko Guild could be a verrrry good life choice for him, since I'm sure that, as traveling merchants, they run on black tea and other high-caffeine drinks!
Verrrrrry nice observations! Hopefully he can find enough cream and sugar to make it palatable.














