Evil Prince, Come Play With Me - Chapter 1063 - When Was Her Period Last Month?

Mark is a genius military weapon designer who was kidnapped by a mafia gang after refusing to work for them.
They forced him to design unique weapons for five years, until one day he successfully escaped only to get shot by his trusted comrades.
*Ding! You awakened a weapon system.
When he opened his eyes, he was in a different body and in a different world.
"You want to kill a wild boar without being detected? Forget about bow and arrow. Here, I present you this sniper rifle."
"You want to kill a horde of goblins from the sky? Forget about those flying carpets and brooms. Here, I present you the fighter jet."
"You want to kill a dragon? Forget about taking the help of the S-class adventure team. Here, I present you a nuclear bomb."
Join Mark Spencer/ Lu Zhen as he brings the whole world to its knees with the help of his weapon system.
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Note: Author isn't born in an English-speaking nation and has no editor either. So, please be understanding if there are any grammatical errors.
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James, a brilliant mechanical engineer and passionate history enthusiast, loses his life in a tragic house fire—only to find himself in a mysterious world as the ruler of an island nation. Armed with his modern knowledge and unwavering ambition, James embarks on a bold mission to industrialize his kingdom and build an empire on which the sun never sets.

I was a good looking prince when I was reborn, and because I could do indecent things as much as I like, I decided to make a harem while traveling with a beautiful female elf~

I was thrown into a novel that hasn’t even been completed yet (and turned into a girl…), guided by the omnipresent voice of the unreasonable, amateur Author as he writes the web novel. I have no idea what’s going on, so I have to stick close to the main character to make sure I don’t hit a bad end…Why are you treating only me like this!I’m not suspicious, believe me.I’m a harmless person.“A villain? Not at all.”