MTL - Magic Chef of Ice and Fire - Chapter 219 The secluded real seal opener (below)

“First, a hidden marriage.”“Second, the marriage period is one year.”“Third, you are not allowed to have any feelings for me!”These were his three stipulations to her at the entrance of the Civil Affairs Bureau.She readily agreed and adhered to them one by one.But a year later, is the man holding onto her tightly and refusing to let go still the same cold person from a year ago?“Could you let go, please? Our one-year term is up.”“Wife, the contract you signed is indefinite!”

Kaidan (Kaidan refers to eerie tales of strange, mysterious, rare, or bewitching ghosts and monsters from Japanese folklore.) feed on cognition, wield information as weapons, and use information as currency, existing between the peculiarities of neither life nor death.They exist in human rumors and dwell in the shadows of the world.“Does this mean I will become a Kaidan?”In ancient times, they were worshipped as deities, empowered by faith.“Then I am a deity!”In more recent ancient times, they were regarded as demons and fed on fear.“I will become the master of Kaidan!”However, as the tides of time washed over, they gradually vanished, leaving behind only texts considered to be delusions.“To restore the glory of Kaidan is an undeniable duty of ours.”But you are not yet a Kaidan, hmm, nor a person.“Well, becoming a Kaidan counts as success.”

One day, Luo Jian woke up from his sleep and found himself in a locked chamber where the door and window were all sealed. A note with a few lines written on it was tacked to the wall: “Escape from this room within an hour, otherwise, you will die.”

There is a sequel called Reincarnation Night (轮回之夜) that takes place in the same universe but has different main characters

- Description from Novelupdates

Chen Rui, an otaku from earth, is reborn into a human body in another world, who falls into the legendary evil, brutal world of the devil called Mozu where humans are treated as food. He has to survive while facing horrors of the devil, violent dragons and a variety of power enemies depending on a strange super system chip and his wits. Surrounded by Devil’s beauties such as black-bellied lolita princess, cold queens, violent dragons, charming poisonous devils …

Wanting to live in the Devil’s world is hard! Wanting to live in the Devil’s world as a human is harder! Wanting a human to be the devil’s son-in-law is hardest!

Let us see how a small otaku uses power and strategy step by step starting from an ordinary human to writing a legend as the devil’s greatest son-in-law.

- Description from Novelupdates