Our Last Crusade or the Rise of a New World Novel Volume 4 was written by Kei Sazane with illustrations by Ao Nekonabe.

To rest and recuperate from their dangerous mission, the unit is finally granted a short break at a resort. There, they expect to lounge around in their bathing suits and chill out... But things take a turn for the worse when Iska bumps into a certain witch: Sisbell, the one Iska saved from prison, and the one carrying a secret that she'll never repeat, not even to her own blood relatives. When Alice catches wind that her younger sister was snooping around to collect intel on Iska, she starts to make her way to the desert oasis for another reunion, too...!