The Great Immortal of Love: All My Female Disciples Are Yandere - Chapter 20 - 19. She is the little junior sister! The memories of the past suddenly attack me.

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

A teenager who obtained a life simulator, with the help of the life simulator, went from an inexperienced martial artist to the peak of cultivation, seeking immortals and chasing gods, paving the way for all living beings, and eventually becoming a generation of Taoist ancestors. [Avenue is fifty, Tianyan is forty-nine, escape to one of them! Therefore, everything in the world has a chance of life! ]

Sixteen years old: You broke through the ninth-rank martial artist, in order to deter all the enemies with ulterior motives.

Two hundred years old: You broke the bondage of heaven and earth, opened the body of the gods, and witnessed the way of immortals.

Three hundred years old: You realize the nature of heaven and earth, and prove the way of heaven and immortals.

Seven hundred and eighty-six years old: You have five proofs of the immortal way, one step to the sky, and the position of the monarch.

…

After countless simulations, [You have opened up an immortal path for all sentient beings and are respected as the Taoist ancestor. ]

- Description from novelbuddy

The second prince has come of age. To celebrate the advent of such an occasion, the search for a suitable bride began. My younger sister was expected to go to the Royal Palace as a candidate. However, despite this, she eloped the day before her departure. I, the older sister she left behind, looked almost exactly like her – so much that we were often mistaken for twins…

One month, right? For just one month, shall I substitute in for my sister?

How long I’d been here, I couldn’t quite recall. From this sorry situation, I as always raised my eyes to the sky; a sky in which the great, massive sun was clad in levity. Sunlight poured gently upon all. What a blessing it would have been for the world if only the skies could remain clear. For tomorrow too, and for all days to come, I was to continue to pray for calm. To endure for those who cried, with desperation I remained in prayer.

And then, one freezing, forlorn, soulless, stagnant, drizzly day we died. Or so I thought…