Reborn as the Demon Emperor, but the Villain Is Me?

(This book is also known as Reborn as the Demon Emperor, Only to Discover I'm the Villain; I'm the Demon Clan's Demon Emperor, Yet the System Wants Me to Build an Orthodox Sacred Ground; and I've Already Become the Demon Clan's Demon Emperor, and the System Is Only Showing Up Now?)

Qin Hao transmigrates to the Tianyuan Realm and becomes a member of the Heavenly Demon Clan. After a thousand years of keeping a low profile and growing stronger, he finally becomes the clan leader and breaks through to a realm the demon race hasn't reached in ten thousand years: the Demon Emperor. The Heavenly Demon Sacred Ground he establishes becomes the envy of all demons.

But just after he becomes the Demon Emperor, a System shows up, and this System is a bit... out there!

[Congratulations, Host, on transmigrating to the Tianyuan Realm. This System is here to help you build an orthodox sacred ground and oppose the strongest force in this realm's demon race: Qin Hao of the Heavenly Demon Clan. We hope you can shoulder the banner of the orthodox path!]

“Wait, System, who did you just say I have to oppose?”

[The Heavenly Demon Clan leader, Qin Hao, a Demon Emperor!]

“System, do you know who I am?”

[Your name is Qin Hao!]

“Am I not Qin Hao of the Heavenly Demon Clan? You want me to oppose myself?”

[You are Qin Hao, but you are a human cultivator!]

“Then why do you want me to build an orthodox sacred ground?”

[Gather the chosen ones of this realm's destiny and defeat the Demon Emperor Qin Hao!]

Qin Hao was utterly speechless. He knew this System was a complete idiot.