Zombie-loan

the long version

"Under Chitose's watchful eye, cabin fever sets in as Z-Loan and A-Loan find themselves stuck inside the school with no way out. Between the threat from the zombie horde just outside and the constant bickering within, neither team is safe from the ARRC, each other, or even themselves. And when one of Z-Loan gives in to the basest zombie instincts, will Michiru's power be enough to bring her friend back to the land of the living?" -- from publisher's web site.