It's common

The white stone. The white jewelry that his brother had. The thing that the holy saint was so desperate to get his hands on. 

That was an item that was given to Aaron by a stranger. A man he had never met in his life, and someone he didn't think he could ever see anywhere in his world. Just glancing at the man's features for a brief second was enough for one to know that he wasn't a normal person. 

From his long blood-red hair that reached his waist to his crimson eyes... Even his clothes didn't match the way they dressed on Earth those days. Even before the catastrophe, he had never seen such clothes. The things that the man wore looked to fit more medieval-style clothes than modern ones.

As he had told the commander before, he had met the man only once for a few seconds. Just like how he appeared out of nowhere the day they were confronting the holy saint, the day he met that man for the first time he had also come out of nowhere.