MTL - Wild Princess: Marrying an Ugly Prince - Chapter 3 : Trouble to find the door

In Academy City, magic and science coexist in an unwavering power struggle. Toma Kamijo, an academically-challenged student in Academy City, wields the power of the Imagine Breaker in his right hand, which allows him to completely negate all supernatural powers – as well as his own luck. When he happens upon a mysterious nun named Index, whose mind has been implanted with the Index Librorum Prohibitorum – 103,000 ancient texts banned by the Church – Toma’s luck is about to be pushed to its limits when he finds himself in the middle of a war he never expected!

Violet skies, a world undergoing massive changes, a deficient moon, interlinking voids…
When the world experienced a cataclysmic event,the majority of living things ceased to exist. Although humanity survived by hiding in the last safe zones, humans had to face mutated dire beasts and colossal source beasts that could break through the space barrier and enter the earth at any second.
Luo Yunyang, a young man who grew up in those calamitous times, obtained an attribute regulator and set out to walk the path of supremacy!

- Description from novelupdates

Cayena, the Imperial Princess, was known as the most beautiful woman in the Empire. She was a woman who knew nothing but evil and luxury.

However, she was destined for ruin: she would be used as a chess piece by her younger brother to secure his throne and killed by her crazy husband.

“I’ll make you the Emperor.”

“… Sister, are you referring to me?”

“In exchange, give me freedom.”

She had to change things before she became that Cayena.