Toaru Majutsu no Index: New Testament - Volume 15, Chapter 3: Conversion, or a Change of Viewpoint — Not_Fiend, Not_Enemy.

The World was thrown into chaos with the arrival of monsters but the humans were given a chance of awakening powers.The MC who was once used to read stories like that was now reincarnated in such world.This is his story on how he would proceed in this troublesome world.

(Completed) She and he were born on the same year, month, day, and time, and on their first day of life, their unscrupulous parents arranged their future marriage.From then on... she began to cling to him.As a child, Luo Mengmeng would say in her baby voice to Gu Zhihan, “Husband, I want to marry you,” but he would grimace and respond, “Who would marry you!”When they grew up, Gu Zhihan hooked her chin, pinned her against the corner, and smirked, “Mengmeng, I heard getting married is cheap nowadays, I'll treat you.”From birth to kindergarten, elementary, middle school, high school, and university, they had always been together.[Growth literature, from childhood to adulthood, exclusively adored]

The story starts on earth, after some unknown circumstances, the world was suddenly invaded by monsters from other worlds. Many died and even more turned into zombies, starting what many would call 'The apocalypse Era'.

Rin, a normal teenage boy who lost all of his family members was on the verge of falling into despair when a goddess appeared and sent him to another world that was very similar to a game Rin played before the apocalypse.

Her goal from this was simple, trample on all the protagonists and become the strongest creature in that world for a chance to get back what he thought he lost forever.

Accompanied by a cold beauty, both of them embark on a new journey to become stronger, get back to their world and fix everything.

A decision can destroy the sun, moon and stars. A finger can kill the Heavenly Overlord. While chatting, the Heaven and ten worlds can be annihilated.

A poor little kid walks out from a remote mountain area while holding the Nine Dragons and the Incredible Cauldron. With a control over the time and space eternally, he embarks on the Path to God where he defies the odds of the boundless universe gaudily by fighting against royalty and clashing with the legendary generation.

- Description from Novelupdates