Ake no Joi to Yoi no Majo: Boku to Kanojo no Midara na Karte

Kou is in search for a cure to his special illness. He arrives at visits Hakone, a remote clinic. Despite the spacious clinic with a swimming pool and other facilities, a sole doctor named Babel lives there alone. She diagnoses that Kou's treatment requires contact with the seductive opposite sex.

This is the story of a daily medical examination between an innocent boy and a bewitching female doctor, which can never be told to others.

(Source: Kodansha, translated)