The Lord of Void and Real - Chapter 6 - 5: Making Things Difficult

The ordinary 18-year-old Edo, during a nighttime walk, finds himself in a fantasy world where he gains a mysterious power that could shape his destiny.

A boy from 21st century Earth, met an accident and later was reborn in Naruto’s Ninja World.
He is born in Uchiha Family and becomes the useless brother of Itachi Uchiha and Sasuke Uchiha…. Let’s see how he changed the Naruto world.

- Description from Novelupdates

Allen, an eight-year-old boy from a poor family in the royal capital, is living a poor but happy life together with his mother. One day, however, memories of his previous life suddenly come back to him and he remembers that he is in an dating sim game and that the capital will be destroyed by war if he doesn’t do something about it. If this continues, both he and his mother will be killed! With a sense of urgency, he decides to rise to the occasion in order to save his precious mother’s life and save his favorite character, the villainous young lady Anastasia, the only girl he liked in the game, from her all too tragic and ruinous end. This is the story of a man who isn’t even a character in the game, but who strives with his steely determination and uses all the knowledge he has to turn overcome fate!

Chu Guang, who had traveled to the post-apocalyptic world, discovered that he had unlocked a shelter system and was able to summon creatures named “player” from the previous world.

From that day on, the whole post-apocalyptic world became like a game.