I Was a Sword When I Reincarnated (WN) - Chapter 665

A supreme expert in the Immortal World had died, and a strand of his soul returned to its original body on Earth. Tang Xiu discovered with amazement that ten thousand years passed in the Immortal World, yet only a single year passed on Earth.

Ruthlessly betrayed by his lover and trusted friends, Tang Xiu found that his soul went back to his previous body on Earth, and, despite he spent 10,000 years in the Immortal World, just a year has passed on Earth and many things have changed. Having an unsurpassed knowledge, Tang Xiu will protect his loved ones and go back to the Immortal World to take his revenge.

- Description from Novelupdates

A story about a history teacher gaming-addict with familial trauma, and a peculiar woman seemingly stuck out of time and beyond out of touch.The two have been thrust into the weird and whimsical world of Altros, a planet with divides born of very real superhuman strength cursory of an odd ranking system, and, naturally, species differences.Not exactly the best of news for our resident Scottish history teacher whose ears have changed into fox ones alongside his nine new fluffy tails.First though, Darren, or Lone, or whatever else the weird system claims he's called, has to figure out how to live with his new companion Sofia, for seemingly forever while also just barely managing to survive being stranded on a monster-infested island with a self-proclaimed former-immortal who can see despite being blind, can freely teleport, and who also, of course, seems prone to experience bouts of extreme depression.Not an ideal situation when he himself hasn't been in a great headspace for over a decade now. But hey, at least there's an incredibly expansive litRPG system to keep the both of them entertained, right? That'll fight off the fear of death, surely.

Elena, who spent her entire life as a cold-blooded female knight to avenge her family, ended up dying without claiming her revenge. When she opened her eyes she found that she went back into the past. By day she was a lady in a dress, and at night she carried a sword to change history and prevent her family’s destruction.

Xiao Ze, who was dedicated to the people and vowed to become a generation of Ming Jun, accidentally fell on a little lady.
The little lady was born beautiful and lovable.
So Xiao Ze accepted his life and got the name of fear.

ps:
①The male protagonist has no concubine, and he is dedicated to serving the country.

- Description from novelbuddy