Jikuu Mahou de Isekai to Chikyuu wo Ittarikitari - Chapter 413 - Weight

Xia Yuqing is a shut-in+fujoshi from the 21st century. After an accident, she transmigrates into the body of a young princess forced into a political marriage to another country.

Ding![The Host has died!]A system message popped up in front of Nell's body after his last dying breath.Ding![Dark Evolution has been activated to absorb the death essence of the host.]And then he opened his eyes to find himself in the past right before the battle started.'Ah! Am I back to the past?'Ding![Please choose a partner to start the Dark Evolution process.][Partner Condition: Must be a living creature from the Monster category, not the Human category][Partner Gender has to be Female.]'Partner? A monster?'Nell's heart pounded in his chest, and he felt a cold sweat coming on.'A female monster?'

A Hentai World is a Dangerous Place, Especially if Your Best Friend is a Hentai Protagonist and You Are a Trap.

She is an elder miss from a modern secret society family. She is very cold and heartless, but her appearance is very enchanting. She thinks of men as playthings. She was schemed against and her body was thrown into the sea.