The Damned Demon

Died a Hero, Reborn as a Demon... The strongest Hero in the world killed the Demon King, the most powerful demon ever to appear on Earth. He achieved something which no other hero could ever do. But alas, the Hero never expected his own girlfriend, his own friends, and the organization he trusted to suddenly turn against him and try to kill him. It was the cruelest blow he was ever dealt in his life.