Katrina Hates the Dead #1

Two years ago, a rift to Hell opened. Monsters poured out and tore across Earth. But that became boring, and eventually they settled into a quiet life in the suburbs. Katrina is sick of living in that world, but there's not much she can do, except work a crappy job and kill monsters. Then, one day her old friend's boyfriend nearly dies in her pizza shop, and that all changes.