Kanojo wa Hanayome Kouhosei Tony's ヒロインシリーズ

Shinji has promised to marry her childhood friend Sae but one day before him appears Zero, a maid that works for the Ichijou financial group, she tells him that as the only successor he cannot marry Sae. He didnt know anything about him being a successor or being the only descendant left of the Ichijou family, his parent died in an accident when he was only a little buy and was raid by someone else without knowing any of this. However Zero tells him that if he really wants to marry Sae, he has to look for a woman with a flower mark on her neck. However this is not an easy task since he has to have sex with the woman and drive her to sexual ecstasy for the flower mark to appear! For the sake of her marriage woth Sae he will have sex with whatever woman Zero tells him to...