⚔️Serberia

— These books reveal the secrets of human potential and how to achieve it. I know it might sound dubious, but this isn't a situation where a critically skeptical attitude would be helpful.

Despite her companion's words, they didn't entirely dispel Calentia's doubts. Nevertheless, the girl decided to give one of the volumes a chance. Reasoning that even if the librarian's words were true, much of the physically oriented material would be secondary to the teachings of Gungnir, who was clearly at the peak of his potential, the Argalian chose a volume dedicated to beauty. One reason for this was simple curiosity.
I'm reading the beauty volume; if they, as you said, don't require OS.