What is otaku-hunting? Well, according to this article, it's targetting and robbing young otakus (obsessed fan of animé, manga and videogames). Young as in, they still attend school. Some of these robbers have been arrested. And the reason why they rob young otakus?
"Otaku are weak and they've got money, so we went after them," one of the arrested youths told the police.
I know you have to be wary in cities, but I am looking forward to Akihabara, and stories like this do not put my mind at ease.