The supporting character's harem is very normal - Chapter 9: Going to the Karol Empire?

Before the rebirth, Gu Qingyao wanted to marry him but did not dare to marry. After the rebirth, Gu Qingyao, with the space materials in hand, all day planning to marry him with a huge dowry.

But she don’t know that someone who was also reborn has been thinking secretly about how to abduct her.

Mo Beihan was holding a bunch of things, and appeared in front of Gu Qingyao with a treacherous smile of a big bad wolf coaxing a little white rabbit. Snacks, endless floral clothes!

Gu Qingyao: “…”

She wanted to raise him into a little milk dog, but unexpectedly, he spoiled her into a little wild cat!

A mysterious and strange world, a human civilization lacking power, and a horrible and turbulent world of human life, Luo Kai survived humblely as a prisoner. Pain and suffering honed his will. War and killing promoted his growth. He suddenly looked back. Is already one of the most powerful beings in this world.

- Description from novelbuddy

He went from an ordinary student to a god-level master in manufacturing.
Continuously progressing, processing range from hundreds of meters to tens of atoms, processing precision from microns to nanometers to atoms and molecules, everything was possible.
Wassenaar Accord? The embargo against China? What we have banned are technologies that China doesn’t care much about. Most of the member states have to import technology from China, shouldn’t the member states have a meeting to discuss and bring in China as well?
Forbidden chip sales? Is there a mistake? We barely managed to maintain our low-end market with a large amount of subsidies, it’s already good enough that China didn’t initiate an anti-dumping investigation. President, are you sick?
Hmm, it seems like living cells can be processed precisely as well. Do you need to refine the cancer cells that you are spreading out?

- Description from Novelupdates

Do you know what it feels like to get shot in the face? A bullet straight to the face?

Yeah, it's a type of quick death where you wouldn't have to feel much pain, but I'm sure most people wouldn't love to die that way...

..But that's exactly how Aiden died. He was shot in the face by the leader of the gang he was in, and it was instant death for him. He joined a gang due to the troubles of life, the unfairness of life, and that's what caused his death.

But that wasn't the end for Aiden. After meeting with the demi-gods and choosing a path, he passed through the cycle of reincarnation and was reborn as a baby into a world where superpowers exist...

..A world where your power element determines how far you'll go, a world where not everyone gets to possess an ability, a world where magical beasts exist.

Aiden would have to survive in this world, he'll have to become stronger to do that, he'll have to awaken an ability. Luckily for him, he was granted something no one else possesses...

[ Ding! Ding!]

[ You've been granted the Undefeated System]

With this system, Aiden can become stronger by conquering females, by banging them. This was gonna be of big help to him, the Undefeated System was gonna take him far.

His journey begins...