Certain Magical Index, Vol. 4 (Novel)

Toma Kamijou has gotten permission to leave Academy City and goes on a beach vacation with his family. But somehow now his mother is Index, Index is Pierce Aogami, Kaori Kanzaki is Stiyl Magnus, Stiyl is a crusty old sea dog, Misaka's little sister is the sea dog's son, and Misaka is Toma's little sister--and a certain magical spell is to blame for everything! Toma's caught in the midst of the mysterious Angel's Fall spell in the latest volume of the smash-hit light novel series!