Problematic Little Sister Fell In Love With Me - Chapter 506505

In a world where reality shifts with every roll of the dice, a man daily partakes in an extraordinary game with the gods, his actions dictated by his decisions and the face of the dice. He takes great joy in this game until the tables turn, and he himself becomes a piece on the game board. Now, the dice are in his hands, and it’s his turn to shape his own destiny. It’s time for the Snowman to play his part.

Among the demons, the supreme ones are called “Great Saints.”

A young man leaves his mountain village and travels around the world. By unceasing efforts, he finally becomes a legend of the age.

- Description from Novelupdates

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