Behind the prosperity of modern cities, there is a secret world composed of monsters from the Classic of Mountains and Seas. These monsters coexist harmoniously with humans. Some of them have become stars, some are in charge of large enterprises, and some are ordinary police officers, delivery people, and migrant workers. They integrate into society as humans, but have their own unique abilities. The story revolves around the daily life of these monsters, revealing how they find themselves and maintain balance in the human world, as well as the mystery and adventure hidden behind the bustling city.
