Episode one looks like a slice-of-life comedy about girls who love their school so much they live there. By episode three, you realize one of them has been dead the entire time, and the world outside is already gone. The show doesn't warn you before it breaks your heart, which is exactly why it works: you're laughing with these girls before you understand what you're actually watching. It moves between cute club moments and genuine dread without flinching, making the happy scenes hurt more than the scary ones ever could. What kills you is that even knowing the truth, the girls keep trying to give each other normal days. That's where the real horror lives.

Four girls, their club adviser and a puppy live inside their high school as members of the School Living Club, whose one rule is that everyone must spend their whole life on school grounds. Cheerful Yuki Takeya adores the club and thinks school is a wonderful place. That picture is a delusion. A zombie outbreak has turned nearly everyone else into the undead, and the club is confined to a barricaded section of the building. Yuki's clubmates, president Yuuri Wakasa, Kurumi Ebisuzawa and Miki Naoki, along with teacher Megumi Sakura, see the truth, and their most important job is letting Yuki keep her peaceful illusion safely. What looks like a gentle slice-of-life series turns into psychological horror, where losing touch with reality may be the only hope of survival.