Rebirth in One Piece as Deputy Captain - Chapter 522

In a future timeline, the earth was visited by a species known as the Slarkovs.
Having lost their home planet and in search of a new one, earth was the next habitable planet for them.

Humans and Slarkovs made a deal with each other in return for the Slarkovs living on earth.
The Slarkovs traded their technology and knowledge for a new home.
They were similar to humans except for some of them who had slight differences so fitting into the society wasn't a problem.
Over the years Slarkovs and humans began to mate with one another and reproduce offsprings.
This in turn created a new species known as the mixed-blood.
Centuries later mixedbloods could tap into their bloodline and perform unimaginable feats.

Gustav born into an age where bloodline determines everything, struggles to fit with a useless bloodline.
His bloodline only grants him the ability to change his hair color, destroying his hopes and dreams for a great future.
His fate is turned around when an unexpected situation leads to him finding a system that grants him the power to unlock and upgrade bloodlines by completing quests but he's baffled by two quests with a five-year deadline. Success will grant him unimaginable rewards...
But only one thing awaits him if he fails... Death!

Follow Gustav on his interesting journey filled with unprecedented adventures, danger and death, maybe?

Living an unfulfilled life, Zack Gray meets an untimely end–that is, until he’s given a second chance, in a new world, under a new name: “Leon Schoeller.” Heir to the Schoeller Estate, a powerful and prestigious noble family, a life of luxury surrounded by maids and butlers of elite skills of their own awaits the reborn man.[Lord System Activated.]In addition to being blessed with a genius mind and magical talent, the [Lord System] grants Leon supernatural abilities, from empowering his servants, conquering beasts, and even manipulating his mansion.However, as gifted as he finds himself, the world around him is full of lurking threats, forcing him to level up if he expects to keep his cozy life intact.

An ordinary student, a wretched peeper, a cowardly teenager with a kind heart. In a terrorist attack, he inherited the knowledge of countless elites, embarked on a path of God Jagged Tu…

He is an artist!

He is a mathematician!

He is a psychology Doctor!

He is a master of fighting!

In fact, he is a man

Taken off raw site:

A wretched, dirty young man is working during the summer when he was caught up in a mysterious explosion. After that explosion, the young man is then left with the memories and knowledge of dozens of the world’s experts.

He has changed, his heart has become cold, iron-blooded. He became a killing machine, his mind turned mechanical, calculative. Everything goes according to his plans and calculations!

In this magical, slaughterous world, a door is opened for him…

- Description from Novelupdates

[Welcome to the Type-Moon System!We offer our most sincere blessings to you, our user.As a beginner, you’ll receive our initial care—a single free draw with a guaranteed five-star.Additionally, you'll enjoy a beginner’s privilege: a guaranteed strategy draw (up to three stars) until your beginner phase ends.Moreover, if you decide to become a player now, you'll receive a pocket dimension for storing your items.You'll also be granted special transmigration privileges, letting you experience what it's like to be the protagonist.So, what do you say? Are you interested in joining?]The boy sitting in front of the computer made up his mind and pressed the “Confirm” button.At that moment, his consciousness froze, and a black hole appeared before him, swallowing him whole.In the dimly lit room, the computer screen still glowed, displaying an unsettling line of text, as if it had snared its next victim.[Welcome to join us.]