Tsuyokute New Saga (LN)

The Demon King led his army of demons to wipe out the human race. The Hero, Kyle, and his allies attack the Demon King’s castle to defeat the Demon King.

The Demon King is slain, but at what cost? Kyle lost all of his allies throughout the war. Friends, family, lovers, comrades. All dead. As he lay dying at the foot of the Demon King’s chamber, he notices a strange gem that the Demon King had coveted.