Humanity's Greatest Mecha Warrior System - 13 Chapter 13

Shao Di Yu, an orphan, is adopted as a result of of a murder case involving the deaths of his entire family. Because of some painful experiences, he refuses to speak. However, he has sharp insight; moreover, he becomes under the care of a pair of twin brothers in the police force, who also have a child currently in university. Yu Yin possesses yin-yang eyes, which allow him to see things ordinary people cannot. The two brothers happen to complement each other, and together they investigate various inconceivable incidents.

Lan Xuan smiled gently as she said, “My dear sister, who told you to obstruct my path? Your man belongs to me, your dowry belongs to me, your everything, belongs to me.”

I am the most talented guardian of this era!

But no one knows, I still have a second template, the knife cuts the flesh, the intention cuts the soul!

You may have seen the meatless juggernaut, but you have never seen a full-time meat shield with an explosive attack!

- 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