U-Ghost (U령)

In a world ravaged and overrun by zombies, one dilapidated, abandoned hospital somehow remains functional. Felix awakens there, having been treated. He encounters El, a nurse whose body is partially zombified. Felix, who knew El from before she became a zombie, is shocked by her monstrous form. Suddenly, Victor appears, claiming to be El's boyfriend and the hospital's only doctor. He suggests that the 'treatment' El needs to survive is sex, and invites Felix to participate... Original Webtoon