This Beast-Tamer is a Little Strange - Chapter 211 Relic Core

The first great emperor in the world was betrayed by his confidante and perished. Millions of years later, the great emperor’s soul returned and was reborn as Ye Yan, the son-in-law who was kicked out by the Chu family with a letter of divorce, restarting the supreme journey. Open the gate of immortality, kill the Jiuzhongtian, and cast an invincible name again!

- Description from novelbuddy

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

It was just a game, one Evan played way too much, but it was still a game in the end. At least it was supposed to be...

However, on the day the main quest ended, he discovered it was more than just a game.

The world of Aidos was real and the demon threat was even more so.

He was sent to be the leader of the new generation heroes and save the world from the demon invasion by the god who made the game.

Unfortunately, nothing was as simple as it may have seemed.

As the truth behind the invasion and the previous Seven Heroes was slowly revealed, he began to have second thoughts about his choices.

He began questioning if the demons were truly the enemies of Aidos.

Even more so, when he discovered a new truth.

That he may not actually be who he thought he was.