Heroines, something wrong with them?

Loid suddenly found himself transmigrated into an apocalypse harem novel. But from the very beginning, nothing went according to the original plot. The future knowledge he was supposed to rely on became useless, and the world he thought would be easy to survive in only grew more dangerous with each passing day. To make matters worse, his system betrayed him right from the start. Maybe it took his joke too seriously... But no matter what, the system was still the only thing he could depend on. However, there was another problem. Why were they even here? According to the story, they should have been trapped inside the university... Oh, right. He couldn't trust the plot anymore. This world was completely messed up.