The Demon King's First General TDKFG

Read at least six chapters, then prepare to crave the rest.
The main character will show up in Chapter Five, though I don't recommend skipping the first four chapters.
-----

The world was celebrating. The Demon King was dead, along with his Darkness Generals.

Humans led the other races to war for subjugation. They killed all, and none were spared. However, thousands of years before this happened, a piece of history was altered by time itself. 

In fact, the Demon King didn't have four generals but only one, which he sealed and sent into eternal slumber. Just as he started to close his eyes, the chains locked away for eternity shattered into pieces.