In Tokyo, monsters and humans live together. The difference is probably that humans live where the sun shines, while monsters live in the dark. Although some of them are good in nature, there are still a few who are evil. Those monsters are just like people, selfish and greedy, but in some places they are more outrageous than people.
In order to tame these monsters driven by desire, someone established an office equivalent to a guild, the Demon Exorcist Office. Specializes in helping people eliminate demons in exchange for money.
But this office is very mysterious. People have only heard of it but have never seen it, let alone entered it. It is said that only those who are troubled by monsters will see this office. Whether the truth is like this or not, who knows.