Nageki no Kenkou Yuuryouji

Hiroe Ogawa is a healthy, normal girl with an extraordinary, private dilemma. Hiroe is unable to reach sexual climax under any circumstances. Over Hiroe's objections, older housemate Mayaka and landlady Yayoi use a variety of sexual techniques, appendages, and even hypnotism in order to help Hiroe achieve her elusive goal.

(Source: Anime News Network)