Dungeon Diver: Stealing A Monster's Power - Chapter 724

Life never seems to go Huai Shi's way. No friends, no family, no money... And when he tries to get a job with his cello at a club, he almost becomes a gigolo! This is no way for a main character with a cheat code to live... But when the supernatural finally starts catching up with him, he begins to wish it never did.

She fought in the Battle of Changping and witnessed the killing of hundreds of thousands. She once led the Qin Iron Calvary and battled against the Six Kingdoms. She has seen a third of the land and witnessed the breaking of mountains and rivers. The sound of a grand zither and the light of a great female emperor. A prosperous world that was forged on the battlefield. Yet, these two thousand years are forgotten from history.

- Description from Novelupdates

She was originally the young miss of the Marquis Estate, but became a peasant girl due to a mixed-up at birth.

Sagiri was born in silence, no cry, no breath, no heartbeat, until a pulse of ancient energy tore through the air and marked him as the last child of a dead people. Cold, disciplined, and frighteningly calm for his age, Sagiri has spent his life hiding a power even he doesn’t fully understand. He does not smile. He does not fear. He does not allow anyone close. Because the thing living inside him 'The Echo' never sleeps.