They probably can't hide from anyone even part mazoku, then. "It has to do with believing things in the face of contradictory evidence. Oh, I don't doubt that they're good at hiding while at work, Scraggly-san, but people known for being stylish and for a prestigious school, I suspect you very much know, when you encounter them under other circumstances that they're there, who they are, and that they're assassins. So not seeing any here means that any who might be around are either already at work and it's pointless for you to worry about them or aren't the ones you're familiar with."
"That doesn't mean that all librarians know it or are as strong as the one you're thinking of."
Decided they had to be replaced in the end. I just couldn't trust them anymore. :( I was going to keep them for spares, though, but the eyeglass place destroyed them. n,n;;;;