The Otaku In 10,000B.C.

Mary Anne runs away from her house. The reason? She lives in a family that, throughout their history, has only given birth to women. And oddly enough, each and every woman born into the family has been born a total nymphomaniac (A family of sluts…. What are the chances?). Not willing to come to terms with her own heritage, Mary Anne leaves her house and joins a Convent. Now known as Sister Mary Anne, she proceeds to help people with their problems and fight off her womanly urges. But it seems her solutions always end up involving sex. And to make matters worse, her mother and sisters have taken it upon themselves to awaken Mary Anne to her true nature. What's a Nun to do? (From Baka-Updates Manga)

Ota-kun, the otaku gets transported in time to 10,000 B.C., where he conquers unsuspecting prehistoric women with his knowledge of modern sex.

Nanami is apologetic about her huge breasts constantly causing problems, and it doesn't help that she is very weak to having her breasts fondled. She decides to join a very exclusive feminism seminar to learn to be an independent woman. (From MU)