The Martial Emperor with Dragon Blood - Chapter 618 - Purple Residence

Living a dual life, Lucas was a meek boy in school and a Wire Knight on the Internet at night. Surprisingly, he's asked out on a date by one of the most beautiful girls in school.

However, the date ends after a bizarre sequence of unfortunate events, he gets isekaid into another world.

Lucas received a rebellious system and some strange pills as rewards which released the dormant evil within him. He has to control the rooting darkness coming from the previous protagonist of that place and learn how to control his power.

The system promises to fulfil one wish if he will win the game he was sent to. This motivates him to help his sister to get better and become healthy again, he must obey the system and win the game to be granted that wish no matter what.

To form a team with another human, an elf and a so-called 'sex machine'. Lucas has to collect all the avatars and learn how to control them, wield the weapons that were given to him and win the tournament of the place by killing the black wizard.

Time is quickly ticking and there's a huge mess for him to reverse. Starting from his date who suddenly was transformed into a dragon!

“Look at you, you were this teeny-weeny when you were little.”Using both hands, Shao Zifeng gestures how small his pet beast used to be. He then raises his head and looks at the gigantic being in front of him.“Just how did you grow into this ferocious form?”

“A cheat system? Do you take me for a fool? Nowadays, where can you find such a good thing falling into your lap? Scram from my head. Is this is new kind of fraud? Or is this a murderer training system of aliens that contains the ability of hypnotism?”

“No, I am the chaos that whispers from nothingness, the nightmare of all living beings in the Southern Ten Stars, the successor of the unparalleled God and… your elder sister.”

“…I only have a younger sister, I don’t have an elder sister!”

“No, you have one. I am an illegitimate daughter. It’s just that your dad didn’t inform you.”

- Description from Novelupdates

Once upon a time, a hero had been summoned to a different world in order to defeat the demon king. After the war stretching 3 years ended the commendable hero slew the demon king. And he was forcibly deported back to earth after being dismissed.

Such bullshit!

Elves in addition to beast race, dwarfs and demon race. Even though I wanted to make a harem in the different world I saved! My dream will not come true on earth, where there is no magic at all. Thus, the hero returns on his own. Without the blunder of being extradited to earth this time, he will build a harem of his own in a different world.