Kindan Shitei de Breakthrough ~Boy Meets Satan~

Description:
The Hero's son and the ghost of the Demon King are the master and disciple!?

Earth, the son of Hero, the Hero who defeated the Great Demon King, is troubled.
Always expected to achieve great things, but unable to meet those expectations.
No matter the effort he puts in, and the results he obtains, it's never enough.
“You're a disappointment compared to your father.”
“Don't you know you're the son of the hero!!”
Living every day like this, Earth meets his destiny in the room containing his father's sword.

“Interesting. I will train you. I have only free time now.”

Earth receives special personal training from the Demon King just to get back at his parents and the world.
In the coming days, his parents, the heroes of the past, his first love, his princess childhood friend, the...