Metaplot: Yuusei's pretty new still so he probably doesn't even know about the search for these artifacts. He won't do much about them for this event, probably.

Personal: Yuusei's probably never actually seen a library before, so he's going to probably give as many things a quick glance through as he can if the topic interests him - mainly looking for stuff about mechanics (the subject, not the people) from other worlds but will maybe look through magic things too - but ultimately his heart might pull him toward some sort of information on golems, particularly machines fuelled by magic.
tldr; he wants a book to build little magic robots

I can write little stories for him, maybe, but only if anyone's interested in it.