TL:
Whose hair is this that was stuck in the book?
Oh, it's your little sister's, huh?
That checks out, your sister does have long hair, Otaku-kun.
But, you know, Otaku-kun,
Just because she's your sister doesn't mean you can let your guard down.
It wouldn't be strange if she noticed your charm, right?
Just to be safe, why don't you stay at my place for a while?
(You're mine, Otaku-kun,
I have to protect you properly.)