Nagi Kodachi

Height: 152cm
Three sizes: 88-56-82
Birthday: December 31

She is the not-so-friendly neighbor of Kyoutarou who seems to be extremely lazy. Interestingly enough, she always warns Kyoutarou about his actions toward the Library Club and the girls around him.

She is actually the one who uses magic for Kyoutarou to experience the Library Club with so many girls, thus implying all of them have actually been forced to join. She is also the childhood friend of him that has always admired him.

It is later revealed that she is the little sister of Kyoutarou after calling him "Onii-chan."