Creatures such as demons, gods, and monsters are collectively called monsters.
They have advanced abilities that humans are afraid of, and can travel through human spaces and worlds at will, but humans cannot reach their world... Everything is beautiful in the peaceful human world after the war between gods and demons, but there is still unrest in the monster world. Some monsters came to live in the human world to avoid the turbulent war. They disguised themselves as humans, lived their own "human" lives in various places, and worked hard to adapt to the way of human life...
However, humans have developed rapidly and invented various instruments. In order to obtain the power of monsters, such as the eyes of cat monsters that can see everything, the precious gold and silver horns of unicorns, the immortal blood of vampires, etc... They continue to hunt monsters, and thus the monster bounty hunters appeared. The lives of monsters living in the human world have been seriously threatened, and their lives have also been seriously affected.
On that day, this group of monsters from the monster world suddenly received a letter, so for the same purpose, they came to this apartment called "Monster House". This apartment is a place where humans are timid. Only pure-blooded monsters and humans with special physiques can enter... And each monster can sign a contract with the monster bodyguard it wants to become a master and servant. Of course, if the ability is strong enough, there is no need for a bodyguard...