Martial King's Retired Life - Chapter 36Book 15:

“Crossing over to a fantasy world of magic and battle auras, Lei Luo accidentally crossed over to the Xiluo Magic Academy and became a librarian.

Raon’s entire life had been lived as a dog on a leash.

Through a twist of fate, he obtained a new life.

Wrath remained in the wreckage of his destroyed leash.

Finally capable of standing on his own feet, he decided to live life by his own will.

He would slay anyone standing in his way…

Even if they were a god.

On his usual way to home Mikado Tsuchio fell into a hole that suddenly opened on the ground. Just like that, Tsuchio falls in a different world, he lands on a Grappler Wyvern and manages to tame it.

Tsuchio decides just like that to live in the other world, the reason for his quick decision: he wants to make a monster girl harem.

Liu Duo was a young girl whose grandmother sold her to four brothers with the intent to be a bride. Unwilling, she ran away the following night, only to fall unconscious while trying to get away. Unexpectedly, however, she was reborn with the spirit of a 25 year old woman, also named Liu Duo.

- Description from Novelupdates