Toaru Majutsu no Index: New Testament - Volume 16, Chapter 2: Attacking a Base with a High-Class Girl - Tower_of_the_Crystal.

Long Fei, a cross-timer and doujin, is an otaku who traveled to another world. In the original world, he was an otaku fan of Gundam and military science fiction.

He died in an accident and was reincarnated into another world. The Gundam works he had read before his death and the techniques in various military novels could be brought to another world.

How would he use the Gundam that Long Fei created? What waves can be caused in this different world?

His Royal Highness the King of Han, who was afraid of the dark and ghosts and loved to cry, has always been the good baby of the princess.
Until one day, His Royal Highness the King of Han found a book in the bookstore…
Picture book?
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Search keyword: Protagonist: King of Han, Princess of Han

- Description from novelbuddy

As a great swordsman who had reached the top level of 999, Lin Feng was hailed as the best swordsman cultivator that the World of the Nine Continents had seen in a thousand years. His sword techniques were exceptional and exquisite.

However, just as he was about to able to enjoy a leisure life, he welcomed another transmigration.

This time, he had transmigrated into a female-dominated world. Women were responsible for providing for the family while men just had to look pretty.

On his first day of school, Lin Feng received confessions from two rich, beautiful, and wealthy girls. The first even promised him a comfortable life as long as he obeys her.

A max-level swordsman in his previous life, Lin Feng would never allow himself to depend on a girl. Thus, he set out on his cultivation journey once again. He would forge a world for men in this matriarchal society.

After being reborn, Bella Green is determined to punish the scum, slap faces, and sing her way to the pinnacle of life. However, she is accidentally picked up by the person she least wants to see and taken home as a cheap 'brother.'Faced with the naughty yet particularly disobedient little Demon King, Mason Bennett sternly instructs: “No fighting, no skipping class, no dating!”One day, the little Demon King shows up on television in a stunning long dress, and Mason Bennett is furious, immediately tying her up and bringing her home for an in-depth lesson!!Looking at her suitors who were beaten up and unable to take care of themselves, Bella's eye twitches, what about the promise of no fighting?Being forcibly dragged out of the classroom and carried home by a certain jealous king while attending class, what about the promise of no skipping classes?Finally coaxed and deceived into the civil affairs bureau, Bella teared up, damn it, what about the promise of no dating!!!