He had adopted a disciple recently to pass his knowledge on. No one but his disciple, the four demon kings and the past kings knew that he still lived. Thus, he and all the past kings went into seclusion in these cave systems, and only came out when something threatening the existence of the entire demon clan emerged.
If not for the feeling of trepidation that had built up in him from the past month that something bad was going to happen, he wouldn't have attended this meeting.
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A day passed with a storm brewing in the demon kingdoms. All the demon kings and ancestors gathered in Duigruzar, upon the invitation sent by the king of Duigruzar.