A Hentai System in the World of Danmachi - Chapter 6 - 5 - Deepthroat. +18

In the year 3021 of the Western calendar, the last world war broke out and the earth was destroyed.
A group of survivors left their homes to settle on new planets. New races, new classes are born. Cities began to be built, countries rose one after another, conflicts between different races intensified, and social order was re-established…
The transformation from a survivor to an aggressor was but a moment.
This is a world where the strong are respected and the fittest survive.
Shang Ping was reborn from the earth in the 21st century to this planet. The moment he woke up, his fate had already begun to change.

Content Labels: Strong Soul Conversion Court Marquis Heaven’s Chosen
Search keywords: Protagonist: Shang Ping ┃ Supporting roles: Solan Edrich, Liu Xi, Austin ┃ Others: future time and space, battleship, interstellar war, rebirth, distant starry sky

- Description from novelbuddy

The world was once at war with 10 alternate worlds. This was known as the Concept War and our world won 60 years ago. All of this was concealed so no normal people are aware of this fact in the current time.

After the death of his grandfather, the high-school student Sayama Mikoto is suddenly summoned by the giant corporation IAI. He learns this world is headed for destruction due to the acceleration of the Minus Concepts. To prevent this, negotiations must be undertaken with the survivors of the other parallel worlds so their 10 concepts can be released.

And so Sayama is caught up in the final battle to clean up after the Concept War which left behind so much enmity.

Lan Xuan smiled gently as she said, “My dear sister, who told you to obstruct my path? Your man belongs to me, your dowry belongs to me, your everything, belongs to me.”

Yang Ye’s entire family relied on him to keep them safe, but just when everything seemed to be going well, misfortune struck in droves!