Ijou Kakusei

The main character is a young doctor who works at a small hospital. He's currently doing research on a disease called Nosfera, and has the ambition of eradicating it.

One day, however, a boy who was a patient in the hospital developed a new type of the same disease, and the symptoms caused him to ejaculate in agony due to the intense tingling of his penis. The new virus then infected the hospital staff as well as the main character who now can't control his sexual urges.

In this crazed state, he creates a secret drug, the "abnormal arousal", that causes more intense sexual symptoms in its victims: an innocent nurse, an arrogant genius female doctor, and a beautiful boy patient.