Rebirth: He Decides to Lie Flat - Chapter 19 - 16: Chance Encounter

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

Alex, killed by the God of Darkness, was crushed by his giant sword and woke up to find himself back on the day the 'Universal Descent' game launched!Monsters and gods hadn't began to descend into Earth yet, and so this meant that Alex, along with his 10 years of experience, could now make a difference.But surprise, once he re-enters the world of 'Universal Descent', instead of awakening his normal C-Level talent, he instead awakens the SSS-Level 'Extraction' talent!He could now extract items, talents, attributes and skills from monsters!Ding![You have extracted the Artifact-Level 'Excalibur'!][You have extracted the SSS-Level 'Meteor' Skill!][You have extracted the Artifact-Level 'World Map'!]Now, there was no monster or god in this game that could stop him!

In this world, orphans or just anyone without any hope for this world can apply to become a “walking target”. Their sole purpose is to be a practicing dummy for the students of the sect who train to become “Demon Hunters”. These students need “walking targets” to test their training on living, walking beings of flesh and blood.
In exchange, they will be provided with food & shelter.
Their existence value is lower than a slave, but if they manage to survive a few years they can receive a life long pension.

Xiao Han is such a “walking target”. One time he witnessed a powerful Demon Hunter disposing a demon. When the demon died, a fragment of the demon that managed to escape entered Xiao Han’s heart. No one saw that, and even Xiao Han himself only felt some discomfort for an instant.

But that thing in his heart soon gave Xiao Han visions, and the first one is of a cultivation method which allows Xiao Han to absorb damage to enhance his body. A perfect cultivation method for a “walking target”.

- Description from Novelupdates