I have an Apocalypse City - Chapter 34 - : Mutated Serpent Beast

Step inside if you dare, but be warned—this is no ordinary shop. Those who enter never leave the same… if they leave at all. A sinister force lurks within, fueled by a dark past and a thirst for revenge. The price? Twelve lives for twelve sins. As officials race to put an end to the bloodshed, the shop’s deadly grip tightens, claiming innocent victims one by one. Will anyone uncover the truth before it's too late? If you crave spine-tingling horror, heart-pounding thrills, and a mystery that refuses to stay buried, this book will haunt you long after the last page.

“Look, I don’t need to be the strongest — I just need to be slightly stronger than the guy trying to kill me.”---Zayn Eldrake was nothing more than a nameless extra in the grand tale of summoned heroes — a disposable swordsman in the legendary Hero of Light’s party, fated to die in an early battle against the monsters of the Apocalypse.But when he awakens in this doomed body with memories of his past life, he refuses to meet the same pathetic end.He knows the story. He knows the heroes. He knows their strengths, their weaknesses… and most importantly, their women.With the power of [Devourer’s Pact], Zayn can consume the abilities of those he defeats, transforming himself into something far greater than a mere extra.Strength, magic, divine blessings — everything in this world is his for the taking. And if fate itself stands in his way? He’ll devour that too.

A black pearl brought Jiang Feng from a doomsday stage where top masters with one emperor, two emperors, three emperors, four deities, and seven peerless cities show off their glory to parallel time and space, and this time and space-the end of the world has not yet opened! !! Under the sky, the youth look up, if I have strength, can I get through … these two time and space! !!

- Description from 69shu

A girl who calls herself a demon appeared before a timid student named Fumio Kijima. The girl claims to be a campaign girl from the demon world and she gives him the ability to “summon a room” from nothing but thin air.

At first he doesn’t abuse his power and uses it as a convenient ability in his every day life. But one day he is bullied by his classmates under a false pretext and is made to suffer. In the past he would have wallowed in misery and cried himself to sleep, but now he had a power to call upon.

“I will make them regret it!”

Using his powers to summon his “room”, he begins his era of confinement and brainwashing to achieve his goals.