Princess Serenade

Main character is a prince and a heir to the king. He barely survives in an assassination attempt with the help of a witch girl and finds shelter in the forest.
He spends there several years to recover under guidance of the witch who makes him reborn as an evil prince, but with former gentle personality. Protagonist starts to kidnap princesses, but all four princesses agree to live with him willingly. To cultivate his evil nature he must learn to insult them, but he is so bad at it that girls have to guide him even in that. Will protagonist complete his evil training and have his revenge or just live happily with the princesses instead?

[From vndbreview]