There is a story within some chapters and some are just filler yet it explore but the life of bianca and the doctor,now the question is why do the trying to hide?
To be honest if that king/church never attack them a peaceful relationship between the king's country will have been done but nooo they just need to become stupid and kill some of rimaru's people and now this is happening tbh rimaru never even wanted to become a demon lord he was force to become...
I will be honest if the king/the archbishop never started the war people and monster can co exist peacefully even if there are demon lords they can still live in peace but thanks to the king/archbishop the world will have another demon lord and many people died (innocent or not)
TL:DR GREEDY...