MTL - The Whole World Wants Them To Get Divorced - Chapter 18

Liola—the best assassin in his world—has vowed to kill no more. He was being chased by an assassination organization when he accidentally dropped into a parallel universe: through a dimensional gate and into poor teenager Kaiser’s apartment. Instead of going to the government shelter for lost dimensional travelers, Liola and Kaiser wind up going to school together.

Liola has been trying his best to live the life of an ordinary person, but after certain things happen one after the other, he begins to realize that being an ordinary person could be harder than being an assassin.

That lonesome night as he lays dying in the hospital, fearing of death and desiring the taste of life, his mind became unprecedentedly complex with mixed emotions.

Blue sky, white clouds, lazily lying on the beach, while feeling the gentle breeze coming from the sea. Hounds at the side with marine animals chasing each other around. Cups of unrivaled wine from his personal winery with cuts of prime A grade steaks readily around. For others, life is all about pursuing money, power, and fame, but for Jiang Hai, this type of lifestyle is what he constantly dreamed of.

- 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