Reincarnated as a Mushroom? - Chapter 75 - 74: Arrival at the Heart of the Ecumenopolis, or How I Learned to Stop Worrying and Love the Bureaucracy

Hikaru Nozomi, an ordinary university student, gets recruited by the Order of the Elements after awakening the Element of Light. And his mission? To find the other 9 Elements.

One day, Luo Jian woke up from his sleep and found himself in a locked chamber where the door and window were all sealed. A note with a few lines written on it was tacked to the wall: “Escape from this room within an hour, otherwise, you will die.”

There is a sequel called Reincarnation Night (轮回之夜) that takes place in the same universe but has different main characters

- Description from Novelupdates

Quinn Winter is a young man from another world. One day, he is suddenly chosen to become the new Demon King. But the Demon Kingdom is in big trouble – it's losing a terrible war against the human kingdom called Gran'le.To help his people, Quinn comes up with a risky plan. He will sneak into Gran'le and learn their secrets. But things don’t go as planned. A powerful noble sponsors him, and he ends up joining Heavenward Academy, the top school for training future heroes.At the Academy, there's a big challenge called the Selection. The best students become Paladins – magic knights who fight demons. Quinn doesn’t want to become a Paladin. He is a demon king! But now, he’s stuck in the Selection… and if he wins, he’ll become the very thing he’s supposed to destroy.He started the day badly. Now, things are getting even worse.

The impostor Necromancer, with inferior forces, is hunted and rejected by others.The genuine Necromancer, with countless skeletons, becomes a ruling sovereign.After obtaining the Double Doors, Wu Heng discovered that his world was overrun with zombies.Plan A failed, and thus began the implementation of plan B for survival.Wu Heng chose to become a ‘Necromancer.’Summoning undead is forbidden in this alien world? The post-apocalyptic planet is full of potential soldiers.Impossible to survive in a zombie-filled world? Then let me live and learn skills in this alien realm.Hence, an undead army armed with modern weaponry made its debut in this world.A calamity engulfs the world, a million skeletons rise.The Dead Bone Dragon, Undead King.(Double Doors + Necromancer + Magic + Fantasy World + Undead Catastrophe.)