One Piece: The Navy's Eight-Year-Old Tech Prodigy, the Four Emperors Have Gone Mad

Xia Yu, after transmigrating, becomes an eight-year-old kid. He awakens a technology system and uses his older brother Kizaru's identity to join the Navy's technology department.
Start by creating a Seraph, upgrade it to General Seraph, and then to Seraph of Lox!
It disrupted the balance of power among the three major forces on the sea, the Navy, and overpowered the Seven Warlords and the Four Emperors!
There is also the Tree of Cosmic Fruits, which surpasses even the Tree of Devil Fruits. The powers of the fruits on this tree encompass all the powers of all worlds!
Iron Man armor, a powerful apple, energy drinks, pacifists...
All kinds of cutting-edge technologies are available!
From that moment on, the entire pirate world went astray...
Blackbeard: You may not know this, but my pirate crew was wiped out by two of the lowest-ranking Seraphs!
Doflamingo: A new era has arrived, but it belongs to Xia Yu alone!
The only way to defeat the navy is through technology!
After the pirates successfully replicated some of Xia Yu's technological products, a race to the top between the Navy and the pirates over technological research and development funding officially began.
The Four Emperors: In order to resist the Navy and replicate Xia Yu's technology, we have spent all our savings!!!
Navy: Do you think we're any better off?
You probably won't believe it!
The Celestial Dragons are all broke!!!
Xia Yu: Back then, you guys were the ones who gave me the money and begged me to develop it.
No money? Is that my fault?