Arifureta Shokugyou de Sekai Saikyou (WN) - Chapter 401

In the tenth year after the new era, the world finally came to an end. Zhang Mu truefully waited for his death, but unexpectedly found that he had returned to ten years ago. With his memory about the future, he swore that he would change the calamitous history, saving the earth from being destroyed! Walking dead, zergs, evolvers, and various mutated animals… nothing can stop him! The first step is to retrieve his identity as an era merchant , then find all the treasures he can remember to enhance himself!

- Description from Novelupdates

“From today onward, you’ll take your brother’s place and take over the inheritance of the Gu family!” With her mother’s declaration, she became her twin brother’s substitute.

Dressed as a man, but unwittingly enticed a lot of sisters!

Incidentally, she also captivated the younger sister of the most powerful authority in China, shouting to marry her!

Ming Shao was furious: “From now on, you will follow me. I will train you to be a qualified brother-in-law!”

Since then, she eats with Ming Shao during the day and lives with Ming Shao at night.

She has always thought that Ming Shao treats her as a prospect brother-in-law, but one day, Ming Shao pushed her down the bed and plundered her mouth!

Hey! Didn’t he say he wants her to be his brother-in-law, how come he turned into her boyfriend?

- Description from Novelupdates

…but it seems pretty doable.

Rei just wanted to read novels in peace, no girlfriends, no drama, no accidental death by divine lightning meant for a cockroach…But for now, he is the son of a powerful duke, reincarnated into a fantasy world full of magic, monsters—and dangerously obsessed women.They were childhood friends of that duke son. They all are sweet noble girls. One is emperor’s daughter and one is my older sister. Now they’re grown up… and they all want one thing.And that thing is Rei.Welcome to a world where love means stalking, loyalty means stabbing your rivals, and marriage proposals come with blood pacts and fireballs and even my system mocks me. Rei fiancées battle each other daily and his life is a romantic comedy… except it’s also a warzone.Oh, and his final mission is marry the Demon Queen. A literal succubus overlord trying to conquer the world.Somebody please help him. In a realm of swords, sorcery, and yandere chaos. So, he can find peace or at least keep his limbs attached.