I Am the Nanny of the Villain - Chapter 142:

The queen’s essential feature is this: [must be a woman or a feminine-looking man].

A former sporting rifle shooter genius transforms into the ‘Juvenile Butcher’. While originally supposed to have received the death penalty, he was instead fortunate enough to have entered a secret and highly regarded armed force, throwing himself into the ‘Nirvana Project’.

From a media tycoon’s daughter to a poor plumber’s girl, but it seems that Yu Yao is unfazed? She opened the eyes of the sky, and her life has been opened all the way. She is an eighteen-year-old girl, but as soon as she turns around, she becomes a big boss who no one in the entertainment industry dares to offend.

- Description from Novelupdates

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.