They are idol worshippers who believe in a god called Zum or Nu.
It is even to the point when he starts a channel on a video platform, it is all about him taking his shirt off.
Women in art were covered in clothing from the neck down, including female goddesses like , the patron of Athens who represented heroic endeavor.
Averted in the original Conan stories, where he usually wears armour or clothing appropriate to the environment.
As non-nudists however you should perhaps attempt to understand why nudists do it.
In many jurisdictions, women who expose their breasts can be prosecuted for , although is often exempted from public indecency laws.
Also, although Kamimura always wears his cloak, he never has a shirt on underneath.
It's unclear if he's wearing anything under the cauldron, in fact, and for a while, some people weren't even sure he had legs though confirms that he does.