Isekai Gamer: Monster Girl Harem Master.

I reincarnated into the Monster Girl Encyclopedia world with the Gamer's powers. On the bright side, I can actually travel the world of MGE and make my own harem. The downside is that I can't level up, so now I'm at risk of being captured and enslaved by just ONE Monster Girl. Author's Note: 18+ scenes begins at the second chapter. — Description from novelcodex.org