A Boy in the Inner Palace

Somehow transported to another world, I lost my memories and ended up in the "Inner Palace" that's full of girls?!If they find out that I'm a man, they'll behead me...! To save myself, I have to do my best to act like one of them. However, one of the girls saves me and soon finds out my secret. "You have to obey my orders... got it?" To protect my secret, she wants me to be her practice partner for her "nightly activities"― All so she can rise through the ranks of the Inner Palace?!The tale of a boy doing his best to survive in a palace full of women!