Re:Zero Kara Hajimeru Isekai Seikatsu - Chapter 99Arc 7, - “Those Who Rule the Sky”

A classic villainess/heroine tale that puts a new twist on the genre. This Industrial Era fantasy tells the story of Nadia—a secret agent with a dry love life and an unhealthy addiction to visual novels—as she Transmigrates into the body of Vivian Moore, the villainess of the novel, from a family of business CEOs.All the destruction flags were raised, and Vivian was at the end of her rope. Her life was about to take a turn for the worst, but with Nadia behind the wheel, she seized Fate by the hairs of its head and yanked it into a sharp U-turn.No more weakness was allowed! If something wanted to get rid of her, she would stab it to death. If someone wanted to trample over her, she would shoot them into a beehive. And there was no stopping her because she had the strongest weapon a main character can have: the System!

Liu Man transmigrated from thousands of years ago to the modern world. Before she transmigrated, she was completely broke. After she transmigrated, she was still worrying about her wealth. And so, for her to survive, she decided to start earning money by becoming a cyber star: trading and selling products, taking photos of her kittens, and showing off bits of her skills. One day she realized, that unconsciously, she had become one of the most famous celebrities.

- Description from Novelupdates

She became the young mistress of the most powerful family in City T by marrying the young master in place of her sister.

He was cold to her on their first nuptial night. "Just because you played some tricks to get yourself married here, you still mean nothing to me!"

However, she was calm and heartless. "Young Master Mu, don't think too highly of yourself. I despise all that is you — your money and your very being!"

After the wedding, Young Master Mu lived lavishly by spending money like flowing during the day while working his nights away busily. "You said you despised me earlier. Well, which part of me do you despise exactly, hmm?"

Luo Chenxi could not bear the harassment any longer so she tossed out the divorce papers in rage. "I can't live like this much longer..."

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