MTL - Invincible Exchange System - Chapter 500 Buckle

Bai Aoxue, the best mercenary in the 21st century, is accidentally sent back to the Chengxi Dynasty in Great Continent due to an explosion in her mission, and trapped in the first daughter of Prime Minister. After her rebirth, she is set up by her father to marry the 5th prince Jun Yeyan who wears a mask all day long.
In the face of bloodthirsty enemies, discord between brothers, collusion among courtiers and invasion of enemy state, can Bai and Jun resolve the crises? What will happen to their political marriage? How will the fierce battle for the throne end?
With many twists and turns, the book brings you to experience palace revolution, love and hatred thousands of years ago.

- Description from Novelupdates

Damien was reincarnated as the villain in a shelved novel. He find himself on a wedding scene where the protagonist was destined to rob the marriage.He smirked while looking at the proud protagonist and arrogant heroine.Aren't you proud and arrogant? Let you know the consequences of offending the Villain!Destroy the background behind you and capture your family!Don't you love her? Aren't you the son of fortune? Kneel Down!!Now the choice is yours! Do you choose your family or the heroine?“Hehehe didn't the heavenly dao want to suppress and kill me? Let's see how I will play with your chosen 'son and daughters' to death! When the auspicious time will come, I will kill you too!!!”

Amid a world war, with his awakening to powerful special abilities (Soul Armor Abilities), Kamiya Yuusuke, conscripted into the military at the age of 10 due to this newfound power, continued to achieve numerous victories on the challenging battlefield. As a result, at the age of 15, he held the position of Brigadier General.Despite traversing battlefields worldwide, he finally managed to return to Japan. The joy of returning home was short-lived, as news of an underage boy in the military started to leak to the public. In response, the military high command ordered Yuusuke to attend a military school called the Special Operations Soul Armor Academy and undergo a revision of his military records.Yuusuke, secretly pleased at the prospect of reclaiming his youth, faced numerous troubles, whether due to the nature of the unique school or perhaps because he had been in constant battle since childhood. What will happen to his relationships with strong-willed girls such as his half-silver-haired childhood friend, the older sister officer who is his work partner, and the tsundere honor student of the same age?

Every human on Earth was transformed into a summoned monster and was summoned to another world.