Toaru Majutsu no Index: New Testament - Volume 12, Chapter 2: Chance Meeting between a Magic God and a Liar — St.Germain,and_LIAR.

She was the most arrogant assassin in the world in the twenty-first century, yet in the end, she was unintentionally killed by her senior brother, resulting in her traveling to Bingzhou continent. The first step after she opened her eyes was to crawl out of the fecal drain and throw the woman who schemed her into the fecal drain. However, at this critical moment, she met a cold and arrogant beautiful man. Looking at his disdainful expression … She would always remember the words of this proud and aloof man. “Once my beloved wife has my child, I will seize Ming You Nation’s land for you and our son!”

- Description from Novelupdates

The end of all worlds approaches.

The Demon King Order harvests lives from all manners of living beings.

Within this darkness full of despair,
A single person escaped from space-time, returned to before the world collapsed, determined to change the fate of the past.

But as time pass, he gradually finds out that the Apocalypse isn’t quite as simple as he thinks…

- Description from novelupdates

I possessed a minor character who marries the prince. I’m not thrilled about it. The prince is a scumbag who flirts with the heroine despite being engaged and eventually gets defeated by the original male lead. In the epilogue, all he does is apologize to his fiancée and marry her, with barely a line to his name. Well, his personality is twisted, but at least he’s handsome. And since he’s the third prince, he doesn’t have to shoulder the burden of ruling the kingdom. That’s decent husband material, I suppose. Go ahead, make a fool of yourself. You’re going to marry me anyway. I’ll just sit back and enjoy watching your embarrassing history unfold. “Doris Redfield. Don’t expect me to ask you to dance at this ball. Maybe not at the next one either. Or the one after that.” “Yes, Your Highness. As you wish.” “Even though we’re engaged… wait, what?” “It’s just a joke proposal our parents once tossed around, isn’t it? You don’t need to take it seriously, Your Highness. I’m really fine with it.” “…Is that so? Yes, that’s… fine, right?” Why are you panicking, prince? You started spouting nonsense first. Where’s your conscience? But then, this guy really has the audacity to ask something outrageous. “…Do you, perhaps, have another man?” The guy who flirted with the original heroine is saying this now? Calm down. He’ll regret this later. All I need to do is remain a devoted fiancée until then. “What are you talking about? A woman like me… plain, not beautiful, with a gloomy personality, what man would even—” “What? Who dared to say that about you?” …You did, in the original story. This guy is acting weird. But he’s not the only problem. “My dear little sister Doris, that dress you’re wearing today is dreadful. No wonder there are rumors His Highness has abandoned you.” “Well, it can’t be helped. His Highness is too good for me anyway.” “…Hold on. Too good? Who said that? Wait, were you really dumped?” The original villainess, who also happens to be my older sister, Natalie, is suddenly interested in my love life. Why are all the original tr*shy characters growling at each other over me now?!

“Why does no one remember the true world?!”