Gaiten Shoku is a series of light novels that physically compile side-stories for the Toaru Majutsu no Index franchise that were originally included in DVD/Blu-Ray limited editions, magazine issues of Monthly Comic Dengeki Daioh, and other various releases.

Included Stories in Volume 1 (2020/6/10):
- Kanzaki Kaori (神裂火織編); 2010/1/29 - 2010/8/27
- Necessarius Special Admission Test (『必要悪の教会』特別編入試験編); 2013/7/24 - 2014/2/24
- Road to Endymion (ロード トゥ エンデュミオン); 2013/2/23

Included Stories in Volume 2 (2020/8/7):
- A Certain Scientific Railgun SS (とある科学の超電磁砲SS); 2009/1/23 - 2009/8/21
- A Certain Scientific Railgun SS2 (とある科学の超電磁砲SS2); 2011/1/26 - 2011/9/22
- Cold Game (コールドゲーム); 2017/12/27

Included Stories in Volume 3 (2024/12/10):
- Agnese's Magic Side Work Experience (アニェーゼの魔術サイドお仕事体験編); 2020/4/30 - 2020/12/25
- Biohacker (バイオハッカー編); 2019/10/30 - 2020/2/28

Included Stories in Volume 4 (2025/2/7):
- Stativarius (ステートバリウス編); 2018/12/26 - 2019/7/31
- A Truly Crazy Way to Get Misaka Mikoto and Shokuhou Misaki to Flirt (御坂美琴と食蜂操祈をイチャイチャさせる完全にキレたやり方); 2025/2/7