I was wondering what good ero anime/manga was out there where the man tries to "train" himself, practicing technique and such with various "assistants", in order to get a certain girl, or get back at that girl. The girl rejected or dumped him because of his performance perhaps, or she bullied him and had her way with him, or she's with a different guy mainly because of how good he is in bed, and he wants to develop enough skill to have his way with her. Nee Chanto Shiyo Yo is somewhat like this, since the guy is basically raped and ridiculed by one of his sisters and his other sisters help him to regain his confidence and develop the skill necessary to take control next time.