Tony's Heroine Series: Kanojo wa Hanayome Kouhosei? Cinderella Collection

Original animation with original character designs by Tony Taka.

Shinji's parents have died in an accident last year, so he has grown up in an orphanage. Now, a year later, he was approached by Maid under the name Zero who claimed that Shinji's father was the only son of a millionaire. His grandfather now intends Shinji to inherit his business. Shinji does not feel great enough to inherit the company from someone he does not know, especially since he has plans for his own life and wants to eventually marry his childhood friend Sae. His grandfather gave him another choice. If Shinji can find a girl with a certain birthmark, she will be given freedom and no need to inherit and lead the company. The only way that birthmark appears is when the girl reaches a climax. How will Shinji make it out of this deal while still remaining true to his childhood love?

(Source: Nekopoi and Has Been Translated and Edited)