Just Because I Have Narrow Eyes Doesn't Make Me a Villain! - Chapter 0: Prologue

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

Struck down amid the battle, the Hero and Demon King meet their demise. As their souls linger on the edge of the afterlife, a mysterious force intervenes, merging their fragmented souls together with a new being. Rusty, the living armor, now affected by their memories and presence, embarks on his own quest. Will he seek revenge on those who betrayed the hero, or will he fulfill the desires of the fallen demon king? or instead, forge his own path?

Jiang Xunyi had transmigrated into a book many years ago, and always tirelessly maintained the requisite accomplishments for a villain.

After finally completing the ultra-difficult task to allow the male protagonist to kill him, an OOC warning had appeared out of the blue——

Error in the actor’s lines, the character role has collapsed, the assigned task has not yet been completed, opening the Rebirth System!

So, he gloriously became… a second idiot son about to be sent to his death.

Lazily idling away the days after changing his identity, he noticed a world-changing difference.

His best friend, the male protagonist, Yun Xie was actually secretly in love with him? Are you kidding me?!

- Description from Novelupdates

Flatten the Devil's Palace, eradicate the demonic cult, slaughter the demon lairs, sweep through the demon realm, dominate the heavens and earth, control the three realms, be the supreme master of the mysterious sect, master of the Nine Yin, the 17th head of the North Star Sword Sect, the Heavenly Fiend Lone Star, the Supreme Sword Soul, the Supreme Infinite Mysterious Heavenly Wishful Great Sword Patriarch... Also known as Iron Egg, known for the wild history of relentless killing.