Isekai Maou to Shoukan Shoujo no Dorei Majutsu - Volume 7 Chapter 4 part2-3

Ukei Kaito fought a desperate struggle in order to fulfill his role as a summoned hero. He defeated the Demon Lord and saved the very world, only to meet an end filled but with betrayal. The companions that he’d trusted throughout his journey betrayed him and killed him by sticking a blade through his chest.

A striking man of mysterious origin and peerless talent, he looks back at the world, in all its entirety, with utter disdain. And yet, in the treacherous and unpredictable ultimate formation of the Boundless Secular World, he guards a breathtaking ancient qin with broken strings, waiting silently for the destined one to arrive!

The little princess of the Huo family, one of the wealthiest families, was mistakenly switched out nineteen years ago! The fake heiress is well-educated, talented, and doted on, while the real heiress is an uncontrollable girl who loves to fight, has a strange personality, and had dropped out of school very early…