SSS-Class Revival Hunter - Chapter 121: The Hero (3)

Two Zatarian youths embark on a cross-dimensional journey to uncover their true identities, encountering both allies and formidable adversaries along the way.They must collaborate to decipher the significance of the symbol imprinted on them, but a faction known as the Nitharians seeks to eliminate them before they can uncover the truth. Naburo, the leader of the Nitharians, has dispatched his most trusted son and his team to guarantee the success of this mission.Will Naburo's son and his team prevail before the Zatarians discover their true selves?

One day, Luo Jian woke up from his sleep and found himself in a locked chamber where the door and window were all sealed. A note with a few lines written on it was tacked to the wall: “Escape from this room within an hour, otherwise, you will die.”

There is a sequel called Reincarnation Night (轮回之夜) that takes place in the same universe but has different main characters

- 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