Loser's redo: Transmigration in a novel - Chapter 6 Felix Root

Fifty years ago, Dragon City transmigrated to the Other World. Alone in the world, they lifted the banner of Earth’s civilization and fought against the terrifying forces of the Other World.

The strongest King of Soldiers returns to the city of flowers, becoming his fiancée's cohabiting bodyguard!

Chen Minhao found himself transmigrated to a parallel world in China, and he even became an idol trainee. By virtue of his efforts in mastering his IQ, EQ, and his looks as his weapons, he became a celebrity with a huge fan base step by step, and ultimately became a global superstar that conquered the both the fields of acting and singing.

- Description from Novelupdates

Tenjou Yuuya has been a bullied boy since the past.He lives in the home of his beloved grandfather while he goes to school. As usual, he receives a harsh bullying, and he takes an extended absence from school to have some time to heal his wounds.While on this long time of absence, he takes the opportunity to clean his grandfather’s house and goes to a room he never went before, where his grandfather keep many different objects that he gathered from his travels around the world. While he was arranging the objects, he found a door not on a wall among the objects.Out of curiosity he opens this door, what he found on the other side was…