Maou-sama no Machizukuri! ~Saikyou no Danjon wa Kindai Toshi~ - Volume 1 Prologue

In a world where magic is a science, Siobhan is a genius.But even geniuses need schooling.When Siobhan stumbled into the theft of a priceless magical book, she thought her dreams of becoming the world's most powerful sorcerer were destroyed.But then a mysterious spell changed her life forever...Siobhan is now wearing the body of a strange man and has a new identity—Sebastien. With a new chance for a new start, she allies herself with a local gang—secretly a revolutionary party funding itself through crime. Now, she is bound by vow to repay them in magic and favors. But as Sebastien's reputation begins to bloom, and Siobhan's old enemies still lurk in the shadows, she quickly realizes that the secrets of this world are deeper and darker than she ever could have imagined.Forced to juggle the two sides of her double life, Siobhan is determined to uncover the truth and take control of the name they gave her - The Raven Queen.

Civilization is destroyed and records lost. Only Dudian survives in a cryogenic sleep. Three hundred years later, Dudian wakes up and must become Dean to survive. Who can he trust in this world overrun by monsters without and within?

- Description from Novelupdates

I found myself possessing the body of a young master who everyone was eager to kill. I’m invincible, so let them try to kill me. It’s only for one second, though.

The queen’s essential feature is this: [must be a woman or a feminine-looking man].