How To Survive A Calamity - Chapter 51 - : Changes

Ever since the appearance of the Tower of Genesis twenty years ago, children's dreams began to change. Becoming a Hunter became the most popular aspiration.The same was true for Nathan Cole. But unfortunately, the Tower had yet to summon him. The Awakening he longed for never came.Until one day, he was suddenly summoned into the Tower. He was overjoyed—but the happiness didn’t last long.Nathan had been summoned… because of a bug.

Reborn as Red Army Misha!

- Description from novelbuddy

After an unexpected death, a soul finds itself reincarnated into the body of Itsuka Shido, an ordinary teenager in a world filled with powerful spirits, magic, and dangers from other dimensions. With the help of a mysterious system integrated into his body, Shido gains the ability to travel across worlds, summon legendary anime characters, and unlock a wide array of random skills and abilities.Disclaimer: The cover isn't mine, credits to the original artist.

A series of short stories in the world of Toaru Majutsu no Index organized into chapters featuring Kanzaki Kaori as the protagonist, going around the world and space doing missions for the Church of Necessary Evil, however, there is more than meets the eye as each incident is connected.

One chapter was bundled with each limited edition release of the Toaru Kagaku no Railgun anime DVD and BDs, with all of them together being equivalent to a single normal Toaru Majutsu no Index volume