The story takes place in Demon City Shinjuku's universe and features common characters.
The district has become an isolated slum in which humans struggle to cohabit with monsters and demons every day.
In this dark place, a young private investigator specialized in missing people, named Setsura Aki, gets routinely tasked with dangerous missions that pit him against the worst entities of the netherworld.
It was divided in two blocks: the Nonnoberu short story collection and the longer Chohen arcs, both started the same year and finished in 2012.
The latter's Demon Princess arc was published in English speaking countries by Digital Manga in 2009.