MTL - From the Head Pillar Tanjiro, Take Stock of the Wonderful Nicknames of Zongman - Chapter 610

Ye Fan accidentally obtained a billion crystal technology system, and since then, he has become out of control.

Android: You do n’t even have a mobile phone system. I want to make it impossible for you all!
Ye Fan: Sorry, I researched it out, it seems to be more powerful than yours!
BMW Benz: Our engines are famous all over the world!
Ye Fan: Sorry, I do n’t have an engine, I only have magnetic levitation, and the speed is only a few times that of yours. Do n’t worry, take your time!
…
Enemy: Is he still human?
Who can stop this!

- Description from Qidian

Yeon-woo had a twin brother who disappeared five years ago. One day, a pocket watch left by his brother returned to his possession. Inside, he found a hidden diary in which was recorded “By the time you hear this, I guess I will be already dead….”

Crossing to One Piece world, he became Roger’s younger brother.

Year 2056, in a city in the Yuan Jiang Su Jin area. On top of a ruined, shattered six story residential apartment sits a teenager wearing a combat vest, militaristic trousers, and alloyed battle boots. On his back is a hexagonal shield and equipped is a blood-shadow battle knife. He sits there silently on the edge of the roof. At this time, the sparkling sky was shining and there was a refreshing breath within the air that blew towards him. However, there was only silence within the ruined, deserted city, with an occasional howl that makes your heart skip a beat.