The World of Otome Games is Tough For Mobs - Volume 7, Chapter 9 “Mastermind”

Science and Technology Library: The supreme state of science is theology; an accidental rescue, let Chen Mo get a technology library that collects endless technology, the story begins…

- Description from xbiquge translation

This is an extremely difficult game, if you don’t have enough skills, don’t even think about going out!

- Description from Novelupdates

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.

[Class changing to the hidden class, Demonic Swordsman.] [You are the first one to discover the hidden dungeon.] [You are the first one to discover the hidden…] [You are the first one…] [You are…] I’m a gamer who uses ESP.