MTL - Unlimited Machine War - Chapter 2750 Where is this especially used

Humanity had finally ended the war with the Demon Race and sealed them away, forever.However, they now have to face the treat of the Shadow World, an equally dangerous threat to their civilisation under the rule of the Emperor!Facing only misfortune from a young age, Nikolaus Reinhardt never expected anything good to happen to him.But his world completely changed when he awakened as an Ascendant, and accidentally summoned a member of the Demon Race in his house.Just because he messed around with a god damn book!

As the daughter chosen by the Heavens, she was already extraordinary from birth. However, with her talents concealed, she was treated like tr*sh and mercilessly betrayed. So, she decided to let her supreme capabilities shine!

From then on, her bloodline had been awoken. Everything was possible—refining antidotes and weapons through alchemy, taming the dragons and phoenixes, and even being the ultimate ruler of the world. Since then, millions of people admired her and she lived up to her name as the strongest concubine in the world!

Only that cold, evil and immensely domineering Ice Emperor, whom she had accidentally provoked, loved, protected and helped her everywhere…

“Oh dear, after he has treated me like that, how can I ever like someone else? This man is really cunning!”

Seo Tae Hyuk, jailed after being falsely accused.

The story starts on earth, after some unknown circumstances, the world was suddenly invaded by monsters from other worlds. Many died and even more turned into zombies, starting what many would call 'The apocalypse Era'.

Rin, a normal teenage boy who lost all of his family members was on the verge of falling into despair when a goddess appeared and sent him to another world that was very similar to a game Rin played before the apocalypse.

Her goal from this was simple, trample on all the protagonists and become the strongest creature in that world for a chance to get back what he thought he lost forever.

Accompanied by a cold beauty, both of them embark on a new journey to become stronger, get back to their world and fix everything.