Rebirth Of The General's Granddaughter - Chapter 22: The scum fell sick

My Beautiful Teacher tells the story of a university graduate Qin Chao who can’t seem to find a job and is in a downward spiral in his life. Then one night as he walks home from another failed job interview, a vase hits his head, making him get possessed by an old and powerful evil spirit sealed in that vase and following another incidents, inadvertently saved a mysterious university teacher Su Ji, thereby opening his path to cultivation, he also manages to get a job as a security guard at Guangyuan School. A series of adventures then took place as he deals with all kinds of supernatural beings.

Ling Xiao was a powerful martial expert who fell in battle and was unexpectedly transmigrated into another world. He began life anew in the body of a boy with the same name, a fallen genius of the Ling Family whose cultivation had been crippled in a surprise attack, and son to a father who had also suspiciously been crippled under similar circumstances. Armed with knowledge from his previous life, Ling Xiao aim to restore his strength and establish his place at the top of this new world

- Description from Novelupdates

He became a teacher at the best magic academy in the empire.
….For being mistaken for someone else.

This legend tells the tale of the protagonist, Kuroki summoned to protect the demon king from the hero.

Kuroki, unbeknownst to him, suddenly came to another world. He was summoned by the demon king, Modes. The territory which the demon king overrules was in the midst of being destroyed because of the hero. He had no choice but to bow before Kuroki.

“Please save us, Savior Dono!”

Kuroki nodded, deciding to save the demon king due to an unexpected turn of event.