The cover of this doujin appears to Five and Man Eater in school uniforms and... on a date...? at a cafe.

Inside, the first few pages do appear to be a cute date, but then they both abruptly drop unconscious and the scene fades to black. The remainder of the doujin is them waking up in a warehouse and killing every one of the cult that kidnapped them. The premise seems to be that they were impersonating a pair of middle school students to bait them out, but it seems to have been mostly an excuse for gratuitous gore.