いじってプリンセス外伝 シャルロット受難

Main character is a prince who lives happily with six princesses full of flirt and love. But Charlotte does not return after visiting national festival. There is a witness who confirms that Charlotte has been kidnapped. Girl is confined in the tower of another king and is violated on daily basis. Protagonist risks fusing war between kingdoms, but he sets out to rescue Charlotte anyway.

[From vndbreview]