The Sky Sloth Wilderness in winter is not a good place to visit.
The closer you get to the Hundred Thousand Great Mountains, the closer you get to the Five Evils Basin, the more so.
The Hundred Thousand Great Mountains themselves are already a wicked land, enveloped in miasma, with poisonous beasts roaming, and the climate is either frosty or hot. Even with the inherently strong physique of the Demon clan, it's not very easy to survive here.
The Five Evils Basin is even worse.
The five evils of the viscera are: the heart detesting heat, the lungs detesting cold, the liver detesting wind, the spleen detesting dampness, and the kidneys detesting dryness. This is what is called the Five Evils.
And what the present world detests is a particular 'human' character.
Humans also have five evils, namely kill, steal, lust, deceit, and foolishness.
