One Piece: New Order - Chapter 75: Darkness and Justice

I was reincarnated into another world, and I’ve brought the Horadric Cube from Diablo II with me.
Being a knight is cool and all, but being a wizard is pretty neat as well.
So, which one will it be?

- Description from Novelupdates

After crossing over into the game world he had played before, Su Nan finds himself as a nobleman who has lost his title. At this time, the continent is still a barren wasteland of elements; powerful wizards abandoned this world a thousand years ago to explore the multiverse, becoming little more than elusive legends.Only Su Nan knows that, a thousand years later, the elements will revive, the wizards will return, and the continent is about to enter a prosperous era of magic.So, his task is quite simple: work hard to cultivate and become a wizard, surviving until the age of wizards arrives!“Resource-poor?”“There’s nothing for it; I’ll just have to synthesize everything myself.”Su Nan opens the synthesis cube. This is the story of a traveler with a player panel and a synthesis cube, leveraging a slight advantage of foresight to make a name for himself in a foreign world.

The eldest son of the assassin aristocrat Tuatha Dé.

The skill, experience, knowledge of the previous life, magic, all of which grows his power as an assassin.

Excellent assassins pass through. He was usually admired as the ideal lord, and behind it wielded a blade as an assassin aristocrat.

Until he became the lowest-ranked master, his lonely and luckless life never changed.

Suddenly one day, a descendant injected him with a nanomachine, and the machine started ‘speaking’ to him.

“What? What are you talking about?”

This was beyond the boy’s knowledge, he turned pale.

The Nanomachine linked to his cerebrum realized the User was not understanding a single word it said.

“Who are you, and why are you doing this to me?”

“Nano Mashin?”

The boy’s face hardened.

Mashin was the deity the Mashin Religion worshipped, along with the Sacred Fire.

The religions’ Master communicated with Mashin.

“Um, are you really Mashin?”

The boy knelt down and asked with a trembling voice. At this, the Nanomachine attached to his cerebrum realized it had been misunderstood.