MTL - Legend of Swordsman - Chapter 6306 guess

After transmigrating into a beast world, Rong Mingshi discovered that the people of this world experienced widespread mania. For example, when their emotions were abnormally agitated, they would become destructive beasts. If their emotions were abnormally low, they would shrink into their young beast form.

An ordinary student accidentally traveled into an other universe and became the king of a small kingdom. He had gotten a “Cheating Code” of life and was able to complete something extraordinary. This is the story about a king that was able to conquer continents and leave behind him an ultimate legend that will be recited between every generation to come.

- Description from novelupdates

Shi Yuhan is the most heartless and evil human Song Qinghuan has ever met. He's arrogant, sharp-tongued, ruthless, and heartless towards her. Yet, he asks (read threaten) her to marry him and she has no choice but to agree. She needs to get into the Era Group to investigate her elder brother's whereabouts.Will her sacrifice be worth it? Will she be able to find the truth of her elder brother's disappearance? Will Shi Yuhan continue tormenting her? What's his motive?