Candidate for bride 1

Shinji is a foundling and happens to be in a relationship with cute Sae. But one day fate reminds him of his past by sending the pretty girl Zero into his life. Shinji belongs to the wealthy family of Ichijyo and his grandfather sends him to find his future wife, who happens to have a birthmark on her neck. Unfortunately the birthmark only appears during orgasm. So Zero helps Shinji with a range of different sex techniques and soon after the first jobs appear for Shinji...