The series centers on three youkai - Bem, Bera, and Barro - who venture into a bustling coastal city and perceive an ominous atmosphere caused by immoral human conduct and the mischievous antics of monsters and other youkai. Driven by a sense of duty, they choose to stay and combat the onslaught of monstrous invaders threatening the vulnerable citizens of the city. Along the way, they develop unexpected bonds with allies. Despite enduring continuous mistreatment from humans due to their frightening appearance, the trio persist in their mission to protect the inhabitants of the city from harm. They yearn to be acknowledged for their heroic deeds and ultimately earn the ability to transform into humans.