All was normal at Tenkyo Nai High School. Students came there to do whatever their usual routine was: learn, skip class, talk, pick on, sports, smoke, etc. Teachers can only do their best every day to make sure students are there to learn in a safe environment as well as the other faculty members. Today seemed like it was just going to be like any other day. That is, until some stranger was spotted limping towards the Courtyard. A security guard attempted to see what was going on, but the stranger suddenly attacked and bit the security's guard neck. Others proceeded to help the fallen security guard, but they too were also bitten by the stranger AND the security guard they tried to help. It didn't take long before more of "them" began to show up at the school, which led to the principal making the following announcement:

"Students of Tenkyo Nai, please remain calm. We are currently experiencing a situation on school grounds that will be dealt with immediate. I ask that you and your teachers remain in your classrooms until AAAH!!"

The P.A. was still on, so everyone in their respective classrooms could hear the glass shattering in his office and disturbing noises in the background. It didn't take long for the school to throw themselves into a highly panic state and everyone started running for their lives, including some of the teachers. "They" who started the attack took advantage of this moment and proceeded to make more of "themselves" by biting other students and teachers. Soon the school was infested, and only a few survivors remain. One group has barricaded themselves in the nurse's office, the other in the teacher's lounge. Both of these groups only chance of survival is to work together and escape from the school...but first they must find a way to communicate with each other.