The Protagonist's Sister Is Actually The Strongest - Chapter 303: The Fifth Demon King, The Weapon of Destruction

This is the story of a modern sailor who was accidentally reborn as a soldier of the Brazilian Expeditionary Force, and finally became the largest plutocratic family in Brazil by virtue of his foresight.

- Description from novelbuddy

On her wedding day, she was humiliated; her status as the legitimate wife was instantly changed into that of a concubine.

Once upon a time, a hero had been summoned to a different world in order to defeat the demon king. After the war stretching 3 years ended the commendable hero slew the demon king. And he was forcibly deported back to earth after being dismissed.

Such bullshit!

Elves in addition to beast race, dwarfs and demon race. Even though I wanted to make a harem in the different world I saved! My dream will not come true on earth, where there is no magic at all. Thus, the hero returns on his own. Without the blunder of being extradited to earth this time, he will build a harem of his own in a different world.

Having a rough life growing up, Wang Tong had numerous dreams of living a better life. However, his alcoholic foster father sells him off as a space settler of the distant planet Norton for some pocket change. Soon after his arrival, the Zergs overran the planet and obliterated its defenses in a matter of minutes. What awaited Tong on Norton was more than just an unbearable environment – its gravity alone was five-times stronger than earth – there were also swarms of bugs, constant hunger, thirst, and desolation.

While he lives a year of total carnage and survival, humanity’s Confederation eventually overcomes the Zergs on Norton and the powerful survivor Wang Tong is given a recommendation to a once famous, but now dying military academy where he begins his life anew.