High School DxD - Volume 18 Chapter 3.1

The world that nurtured the civilization which reached the pinnacle of magic was on the verge of destruction.
The last survivor transmigrated to the past, when the magic civilization started growing, as countless mages were still fumbling their ways through the thorny paths of magic knowledge.
He, who came from the end of the magic era, aim to reach the pinnacle of magic.

- Description from Novelupdates

“I’m in desperate need of money to pay Grandmother's medical fee. I will marry Charles instead of Yvonne as soon as I get the money.”

When her sister Yvonne ran away from the wedding, Autumn was forced to pretend to be Yvonne and marry Charles. Her only wish was to get a divorce after a year. Charles is rich and powerful. His name had been linked to innumerable ladies. He had different girlfriends for every day of a year. Neither of them had expected that they would fall in love with each other.

As a precocious child, Lycoris suffers from a strange sense of deja vu. On the day her father told her about her fiancé, she realizes that her fiancé was a character from an otome game she once played in a previous life.

Lin Mu Yu is one of the top players in Conquest the game before Destiny. He decides to delete his account due to a promise with his father.