Claimed And Marked By Her Stepbrother Mates - Chapter 519-It’s Getting Good.

After breaking up with his girlfriend, he accidentally acquired a genius system and rose from there against the heavens, becoming invincible..

- Description from Novelupdates

The elf girl, Aria is an adventurer. Her enchanting, lovely features attracts everyone. Her twin peaks are ripened to the point of exploding. Then, being embraced in between those twin peaks was a little animal… his name is Tama.

He looks like to be a cat at first glance, but Aria and her surrounding companions failed to take notice of single detail. Tama, he’s a human who’d reincarnated, given a second chance at life. His true form, it’s not that of an ordinary cat. Instead, he’s a monster of the strongest class, an extremely young behemoth.

Zhou Donghuang, a man from the Earth, is able to destroy any planet in the universe without lifting a finger. His supreme will can sweep across the vast cosmos in the blink of an eye. And his immortal spirit can depart from his body and wander around the universe!

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