City of Witches - Chapter 16: Border Town (1)

The male student, Fukai Nagamasa, ignores his studies for college entrance exams in favor of following the path to chuunibyou. As he fainted during night cramming session before the exams, he realized that he was transported to a parallel world as a feudal lord in the Sengoku Era. Not to mention that suddenly, he was marrying the sixth Demon King, Oda Nobunaga’s little sister, the one who was purported to be an unrivaled beauty?

It was a life without regret. My parents were in good health, and I wasn’t homey enough for me to combine my studies and part-time jobs.

Mu Zhiyan, after being transmigrated a millennium (1000 yrs) into the future, discovered that he was raised by his adoptive parents as a tool for them to access the heritage his (dead) biological parents left behind. When he was at a loss for what to do next, he discovered that his body hosted an additional
pharmaceutical system.

For a chance to return to his era of Earth, Mu Zhiyan decided to practice and practice; he must train the system to full level as soon as possible.

However, reality gave him a slap in the face. The world is dangerous and dreadful, making Mu Zhiyan recall his mother’s words of holding a thick thigh, resulting in him locking his eyes on a cool general…

So the rumored mysterious Mu Master faced General Han with a serious face: “I allow you to follow me, General Han.”

General Han: “…”

- Description from Novelupdates

She is the Crown Prince’s fiancee, but on the night of their wedding, an edict was made and she was given off to marry the crippled and paralyzed God of War.