A brief description of the manga Mutant wa Ningen no Kanojo to Kiss ga Shitai:
The world was devastated by nuclear war and now there are mutants walking about. The story starts with our friend, a mutant who is desperate a girlfriend, but there are no humans left alive, or are there? The mutant meets a human girl and falls in love with her. In a desolate land, a different kind of love burns fiercely, sadly, and purely!