Worm (Parahumans #1) - Chapter 291: Arc 29: Venom - Interlude; Fortuna

Yang Gang accidentally became the imposter heir to a wealthy family, with a beautiful older sister and a twin younger sister at home...

He, since childhood, had followed the Foreigner to practice the Defying Heaven Art, entering the most secretive special forces and becoming a fearsome assassin that made others tremble at the mere mention of his name. After a single failure, he took early retirement, but he ended up as the personal bodyguard for a rich heiress, a school beauty. Accidentally provoking some mysterious Cultivators, he gradually unveiled a hidden world of Cultivation beyond the mortal realm...

Back in 1998, an ordinary person who has been through, tired, cried, and fought, hopes to run down-to-earth and keep up with the trend of the times.

- Description from novelbuddy

In this world, only if you are strong, can you protect the people you love.