The canal between Upper Town and Outside isn't just geography, it's the show's entire thesis about how societies build monsters, literal and human. Bem doesn't waste time on mystery theater; it shows you corruption rotting from both sides of the divide, then asks what you'd become if you had to survive the bottom. Three inhuman creatures trying to earn humanity by fighting the ugliness humans create is the kind of premise that only works if the show commits to making the ugliness real, and it does.
Libra City stands divided. The gleaming Upper Town glitters with wealth and power, separated from the lawless Outside by a single bridge spanning a massive canal. Detective Sonia arrives in the corrupt, crime-ridden zones beyond the divide to pursue a string of brutal cases, and her investigation leads her to three grotesque beings who patrol the shadows. They call themselves youkai ningen: demon humans who hunt monsters that prey on the innocent. Sonia must reconcile what she sees with what she's been taught to believe. These creatures are hideous, undeniably other, yet they fight to protect humanity with a conviction that suggests something deeper than their monstrous forms. As she works alongside them, questions multiply. What are they really? Why do they choose this path? Can something so inhuman truly care about human suffering? The series unfolds as a noir-tinged mystery where the real monsters may not be the ones with fangs and claws, and where the line between savior and demon blurs in the city's darkest corners.