Yoshiaki Maeda is wrongly accused of murder and sent to Shouran Academy Juvenile Detention Center, where he meets his cellmates Gou Iwakura, Masafumi Yoshioka, and Mitsuru Yamanoi, each with their own troubled pasts. As Yoshiaki tries to navigate the dangerous power dynamics within the prison, a sudden zombie outbreak shakes their world when infected humans invade the facility after a van crash. Now, the inmates and staff must confront this new terrifying reality amidst their own internal struggles.