Dead Ruler

It has been so long since Achilles was reincarnated in Efina. He became the Hero who mastered Summoner Necromancy. 

After defeating the Demon Lord, Achilles decided to retire and live in the countryside. He developed plant insecticides and helped his neighboring Baron with their crop problems.

When the gods decided to damn him out of the blue, naming him Dark Lord and painting him as a Villain in the eyes of humanity, he moved on with his life, caring nothing about their scrutiny.
But their ways are ineffable, and when they start sending Heroes to throw their lives against him, he vows to make them pay one undead at a time.