Lucifer's Descendant System - Chapter 43: Valorwatch

The century long war had just ended and humanity had managed to get their hands on alien technology, sending them years ahead in terms of technological advancement, fulfilling their hope of finding life outside their planet and their desire to dominate these extra-terrestrial existences. The effects of their technological advancement alone wasn’t capable of giving this result.The appearance of mutations which granted supernatural powers among humans was another boon giving them the chance to act out their darkest desires.Their joy took a dark turn when it was revealed that they were nothing more than livestock to the mysterious race, Xillthars, who cultivated them to that level. Like fattening livestock.Shortly before this dark turn of times was a forbidden creature, Kieran who had been born into the lowest levels of a society created by the greed of humans. To him, life had always been hard, but things got worse after the arrival of the Xillthars as he found himself on a trail of shocking discoveries about himself and the world around him.

Kyoukai Senjou no Horizon chronicles the story of a futuristic civilization returned to Earth after constant warfare hindered them from traveling beyond the post-Apocalyptic Earth. At this stage, a small archipelago called the Divine States were the only hospitable land on Earth. In order to regain the space-faring technology they had lost after many years of war, they decided to recreate history with a book called the Testament as a guide.

It is the year 1648 in the Testament Era. Toori Aoi, Chancellor and Student Council President of the only academy on the airborne city-ship Musashi, faces the ten-year anniversary of the death of his childhood friend Horizon Ariadust in an accident. As he prepares to celebrate the occasion by proposing to P-01s (an automaton who looks exactly like Horizon) he discovers that his suspicion about P-01s’ appearance actually has a basis in truth; P-01s is in fact Horizon Ariadust, reborn into a robotic body. In addition to this, Horizon’s emotions had been stripped away and are now stored in eight powerful weapons called the Mortal Sin Armaments; which are now in the possession of key people in various established countries in the Divine States.

To retrieve the emotions of Horizon Ariadust, Toori Aoi along with his friends and allies begins a crusade against different obstacles as key events in history are recreated in a futuristic manner.

With the revival of spiritual energy and the breakdown of the order of species, it is a difficult test whether human beings can still stand at the top of the biological chain.

(There is already an old book, The Strongest Descends in the City, you can read it.)

- Description from novelbuddy

I was a good looking prince when I was reborn, and because I could do indecent things as much as I like, I decided to make a harem while traveling with a beautiful female elf~