Naruto System in One Piece - Chapter 4: The Supreme Naruto System

Once through the pirates, Lu En became the son of Monkey d Dragon, a grandfather named Monkey d Karp, and an unreliable and neurotic younger brother named Luffy.

Fortunately, the ghost back system is activated!

The completion of the ghost back is 10%, and the training effect is increased by 100 times!

The completion of the ghost back is 20%, and the training effect is increased by 1000 times!

…

One day, Lu En, a ghost-backed master, appeared in front of Luffy who was shouting to go to sea, and made Luffy cry on the spot.

Luffy: “The pirates in the sea are all monsters like my brother? I don’t want to go out to sea!”

Garp: “For a long time, the two boys, Long and Luffy, with small arms and calves, I really doubt that they are not my sons and grandsons. Like Lu En, they are the grandsons of the old man!”

Warring States: “The strongest creature in the sea, land and air is Kaido? No, it’s Lu En!”

- Description from novelbuddy

As Shin Youngwoo has had an unfortunate life and is now stuck carrying bricks on construction sites. He even had to do labor in the VR game, Satisfy!

After his parents died, Alex Roth had a plan: become a wizard. Through hard work, he was accepted into the world’s greatest university of wizardry—but fate had another plan.

On his eighteenth, he is marked as one of his kingdom’s five Heroes, chosen to fight the land’s great enemy. But his brand is 'The Fool', worst of the marks.

Rather than die or serve the other Heroes like Fools in the past, he packs up his little sister, his childhood friend and her cerberus, then flees for the university in hope of refuge, magic and to unravel the truth about his land’s evil.

There’s one small problem: The Mark tries to ruin magic while enhancing skills outside of divinity, combat and spellcraft.…

…that is, unless he can learn to exploit the hell out of it.

Pinning her tall body against the hard wall, he looked into her beautiful emerald green eyes as he spoke in a deep voice, "I have two options for you," his body came closer to hers as he continued, "Be my girlfriend. Or," his lips turned into a sly smile as he whispered close to her ear, "Be my boyfriend." He even dared to wink right before her as his dark orbs glinted amusingly.