MTL - Longevity Begins with Marrying a Wife - ~ Say it (must see).

In the middle of a deserted island, a small boy wakes up with two sets of memories: one from his few years of life and the other from a man who lived to adulthood and achieved great things. When he least expected it, a powerful master appeared on the island and took him in as a disciple, revealing a shocking fact: magic exists in that world, and, thanks to it, humanity managed to conquer the galaxy.

Finding an ancient treasure was not as fortunate as one might expect. As soon as Bai Rouyun had left the grave, countless sects and hidden families set out to kill her for the sake of obtaining her treasure for themselves.

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.

[*Ding*