I read it about a year ago but forgot about it. Now I can't recall the name.

The manga is about these weird doll-looking enemies who are extremely powerful taking over the world. One day, one of them goes to the protagonist's school and kills almost everyone. The protagonist runs to a club and meets up with 3 other people. I remember one of them was a fat guy and another was a girl with really, really big boobs - the kind that hang out and just barely have their nipples covered. They all steal someone's car and drive somewhere. In the sky, there's this huge devilish symbol, and the little doll things can be seen killing everyone. I can't remember what happened next, but later on they were forced to walk through a bunch of fog. The characters decide to hold hands so they won't get lost, but suddenly, two of their heads blow up for seemingly no reason. The protagonist and the boob girl run into a mall, where they encountered a pervert cop who apparently had raped a girl and killed her. Somehow they neutralize him and meet up with the rest of the survivors at the mall.

I can't remember anything past that point, but hopefully that's enough to go by. Thanks for anyone who can help out.

I found it. It's called Magical Girl Apocalypse.