Use first and repay later: Advance the future cultivation fruits - Chapter 543 - 243. Earth, transformation into a second-level civilization

The world that nurtured the civilization which reached the pinnacle of magic was on the verge of destruction.
The last survivor transmigrated to the past, when the magic civilization started growing, as countless mages were still fumbling their ways through the thorny paths of magic knowledge.
He, who came from the end of the magic era, aim to reach the pinnacle of magic.

- Description from Novelupdates

“How can such an unscientific thing be possible?”“If it's true, wouldn't we be able to rule the world?”“You think so, don't you, Mr. Gin?”“By the way, could you please sign an autograph for me?”“Use your real name.”————Since the disappearance of high school detective Shinichi Kudo, the death rate in Beika City has been increasing.But it doesn't matter, Hayashi Yoshiki will take action.He will make the whole world keep up with Beika City's pace.

Ophelia von Aubessec, an Empress ruling over millions gets slain.Regressing back to her body 300 years ago, she sets her sights on getting revenge on the forces who had managed to kill her.By using her knowledge of the future, she builds her own Empire, wins back the lovers she lost, and discovers the secrets of the system she had been provided.---------This is a dark novel and IT IS HAREM. However, it may travel more into a polygamous relationship due to the complications of a harem.There are also R18 scenes sprinkled about, so please read responsibly.