Biased
The leader of the library thinks that all the books in their library are better than everyone else's books. He's a very biased person. If he wasn't the leader of that specific library he'd probably feel differently.
Imagine showing the leader your favorite book. "That's not a book in MY library," he says, and throws it in the trash. That's so biased! He didn't even give it a shot!
へん
かたよ
None
You decide to give in to his biased recommendations and look at what he has in his library. It doesn't take long until you realize that these books are all about hens (へん) and hen care. This guy is so biased about his favorite books that he only filled his library with what HE wants to read. And apparently that thing is taking care of hens... weird.
"This is such biased crap," you say, as you finish reading the title of a book called "Hens are better than all other birds." Screw this leader guy and his books.