Naruto System in One Piece - Chapter 1: The Tragic Crossover

Raised by a league of assassins and trained for thirteen years, Shan Yue was seventeen when she took the throne of best assassin, becoming an untouchable legend amongst assassins.

Despite being legendary, she put her faith in the wrong people and was killed by her own league’s betrayal. However, while Shan Yue thought her death was assured in the violent explosion, she was surprised to find herself reincarnating into the body of a useless female student.

Forget how pudgy and dim-witted she was — she seemed to get into fights every day! Her original body’s sister sneered, “Fatso! All you do is eat… and look at how ugly you are! You really embarrass me!”

Fat? Ugly! Shan Yue started a daily training regiment, rapidly slimming down and becoming a ravishing beauty! Her original body’s mother snapped at her, “How did I give birth to a child as stupid as you?! Always last place in school — you embarrass me!

I should have strangled you right after I gave birth to you!” Stupid?

Last place in school? Shan Yue lifted a finger, and the principal of the top school in the capital personally visited, offering a transfer to his school. Elite hackers, doctors, mercenaries, math geniuses…

All of them were now vying for her attention! Though she managed to get the chance to become normal after going through so much, she accidentally become a big shot again, even finding herself a two-faced bigwig for a husband! Shan Yue: I just wanted a quiet life, but my abilities prevent that. Sigh…

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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In the world of the gods, everyone is a god, develop believers, gather faith, and lift the kingdom of God into the starry sky.

The young Xu Luo came to this world and started the Zerg dominance system.

Ding! Extract the sawgrass gene, and the springtail + sawgrass becomes a mantis insect!

Ding! Extract the snail gene, and the beetle + snail becomes a beetle.

…

Face Huggers + Angels + Dragons + Power of the Ancient Gods become Leviathans!

Extract the genes of all creatures, and the Zerg army sweeps the world!

(Book Friends Group 682275028,)

It can be updated on the shelves, don’t worry about eunuchs

- Description from novelbuddy