The Legendary Mechanic

Han Xiao, a veteran power-leveler in "Star Sea," is thrown by a mysterious force from the east into the ranks of transmigrators, carrying a player interface as he becomes an NPC and returns to the period before the game’s open beta. He decisively chooses the hardest class: the mech system.

Battle fleets sweep across the star sea, stellar mechas soar like dragons, psionic cannons can destroy heaven and earth, and an endless mechanical army lies quietly in the personal storage.

One person is a legion!

If not for the appearance of players, this book would be a serious and solemn isekai story...

As an NPC, he has all the functions a normal NPC should have toward players... issuing quests? Adjusting favorability? Teaching skills?

Wait, why do I know this group of players?

Fine, even the real world has gone back ten years.