Official Sovereign?
This was definitely not a title for himself. The first column on Zhou Ze's credentials clearly stated his name, while the second column clearly stated his position as a temporary ghost servant.
Furthermore, this could not be a form of address to show respect. For example, in the Republic of China, when commoners saw a soldier, they would call him boss. If a temporary ghost servant could be called the prefectural lord, then this kind of title was too common and worthless in hell, right?
Therefore,
The problem should be the small notebook that he had just obtained.
This identification used to have an owner. Even though it had been 'refreshed' because of Zhou Ze, there should still be some information about the previous owner on it.
In short,
He had picked up the item of a very impressive person, and he had obtained it without much effort.
