The series centers on three youkai—Bem, Bela, and Belo—who arrive in a large coastal city and encounter a sinister atmosphere stemming from human immorality and the mischief of monsters and youkai. Consequently, they decide to remain in the city, battling other monsters and youkai that attack humans, and make a few friends along the way. Although the trio is frequently abused and discriminated against by humans because of their appearance, they continue to strive to protect the city's human population from other monsters, hoping one day to become human themselves in return for their good deeds.