The girl Shiki met in the library was the same girl that he had seen riding on the back of Sasajima's bike. The book she left behind has a marker stuck to the page on building quiz bowl buzzer systems. Is she involved with quiz bowl? As Shiki is thinking about all his, Mari tells him they're having a joint quiz bowl practice with another school today. That school turns out to be Miyaura High, the team that claims Mikuriya as a member!
I took the book she left behind because it 
looked like it was hers, not a library book,
لقد أخذتُ الكتاب الّذي تركته خلفها
،لأنّه بدا وكأنّه لها وليس للمكتبة
Ich nahm ihr Buch mit, weil es immerhin
ihr eigenes und nicht aus der Bibliothek war, …
Traje el libro que se le cayó
porque parecía suyo,
Traje el libro que se le cayó
porque parecía suyo,
On dirait que le livre
qu’elle a oublié lui appartenait…
Ho preso il libro che ha dimenticato
perché mi sembrava suo,
Trouxe o livro que ela deixou porque
 não parecia ser da biblioteca.
Я взял эту книгу, потому что она 
не библиотечная, а принадлежит ей.