Mushoku Tensei (WN) - Volume 5

Jian Wushuang was reborn in adversity. In order to get his revenge, he began to cultivate Heavenly Creation Skill. With the help of the Heaven defying cultivation method, Jian Wushuang gradually grew into a peerless genius from an ordinary practitioner. With a sword in hand, no one is his match. Using his extraordinary Sword Principle, he killed all his opponents and eventually became number one Sword Master from time immemorial.

- Description from Novelupdates

“Seven years later, she returned with her baby

”Give me the child, and you can name a price!“

”Spring only sows the seeds. When it comes to autumn, you want to obtain a son. Heh, man, aren't you thinking too simply!“

”If you want me to call you daddy, then you have to show your ability to chase after my mommy. The man that my mommy likes is my daddy! “Otherwise, there's no need to talk about it!”

Before going to college, an ordinary high school student went to celebrate and got drunk. When he woke up, he found himself in a completely different world. There was a big sect, the approaching sect entrance examination, a slum where his body’s previous owner lived, and a shared memory about a missing young girl.

When he got tangled in a fight with a few punks in this different world, he fell off a cliff and miraculously found himself still alive, with two more voices ringing inside his head. They were Sword Master and Saber Master. In the company of them, he continued to find out more about this whole new world. He took the sect entrance examination, entered the sect, met a strange man in black, and even participated in a major competition of the sect to have a chance to win over his peers!
In this whole new world, he was born again and got to explore the fantastic martial world!

- 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