You ran through narrow alleys, trying to hide from the crowd of zombies that were going to eat you. You were driven into a corner and had absolutely no idea how to survive... Suddenly, a mysterious girl in a school uniform jumps from the roof and cuts through the crowd of zombies with one powerful blow with a sword. Then, she adjusts her skirt and looks down at you haughtily. Hmm... Alpha Squad 19, I found a survivor on Shibuya Street! He looks weak, but it might be useful...