Toaru Majutsu no Index Light Novel Volume 21 was first published on August 10, 2010. It is the second novel that depicts the events of World War III for the finale of the series. It features the continuing efforts of the three protagonists with their own individual struggles.
October 30th. Eleven days have passed since the outbreak of World War III. Three boys, with their secret thoughts, had ran into flames in Russia.
To cure the former ITEM member Takitsubou Rikou, Hamazura Shiage is searching for a treatment. The key is his encounter with the God's Right Seat member, the Saint Acqua of the Back.
The "strongest" esper, Accelerator, after a battle with the weakest rival, is being transferred to the Elizarina Independent Alliance. Accelerator still hasn't found any leads to saving Last Order. The key is the magic that contains a mysterious parchment.
Kamijou Touma, to finally encounter Fiamma, used discretion to escape. The event where Index returns to full health has not come true. The key to that is the resident of another dimension who calls itself an "Angel".
Three different hidden feelings, when science and the magic cross, the story starts—!
- Prologue: Battle Report
- Chapter 5: The Battlefield Called the Complicated Tray — Enter_Project.
- Chapter 6: The Unfolding of the True Darkness — Up_the_Castle.
- Chapter 7: Up the Sky is the Slaughtering Angel — MISHA_the_Angel_"GABRIEL".
- Chapter 8: Their Many-sided Counterattack — Combination.
- Epilogue: Battle Report