Animal Tamer's Dominion - Chapter 20: Battling A Fire Sprite.

The low-ranking behemoth, the iron mountain is invincible in the horizontal push, and it is called the king of the backing.

- Description from novelbuddy

Xu Min realized that he was gifted with an exceptional talent for cultivation as he was training to become a family guard. His path was set before him but due to the jealousy of man, misfortune befell him. Xu Min found that he could trust no one as he began walking down the path of vengeance in a world where only the strong survived.

“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 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.