Toaru Majutsu no Index Light Novel Volume 04

Publisher's Summary
Kamijou Touma receives permission to go outside Academy City and goes on a beach vacation with his family.

Then he discovers that his mother is Index, Index is Aogami Pierce, Kanzaki Kaori is Stiyl Magnus, Stiyl is a fisherman, Misaka Imouto is the son, and Misaka Mikoto is his younger sister...!?

A certain magic spell is to blame.

Kamijou Touma finds himself in the middle of the unfolding of the mysterious spell "Angel Fall"!

Chapters

 * Prologue: Parallel World of the Real World
 * Chapter 1: The Magic World's Hex Suspect
 * Chapter 2: Detective of the Battling World
 * Chapter 3: Angel Force of the Harmful World
 * Chapter 4: The Last Wizard of the Single World
 * Epilogue: My Betrayer of the Everyday World