Detective Anko Uguisu and her young assistant Kou Yamori find themselves drawn into a new investigation when a young woman in disguise arrives seeking their help. She is Amu Miyamoto, a rising idol who reveals that her fellow band member Mei has become entangled with a mysterious religious group called Paradise. This isolated rural commune is led by a charismatic and ageless guru named Lady Ushio, who promises her followers youth and eternal life, hinting at a vampiric nature. The entire village, which the cult members call Paradise, refers to themselves as offspring, but the truth behind Lady Ushio and her promises remains unclear.

As Kou and Anko travel to the secluded countryside where Paradise is based, their arrival is met with suspicion and hostility from the inhabitants. All signs point to vampires being involved in running the cult, though the specific goals of this particular group remain a mystery. While investigating, the pair discovers that no one ever leaves Paradise alive. This side story is set in the timeline between the final two chapters of the original Call of the Night manga, which concluded with chapter 200. Notably, the series' protagonist Nazuna Nanakusa does not appear in the early part of this arc, instead allowing the focus to remain on the detective duo and their investigation. The Paradise Arc ran as a limited serialization in Weekly Shonen Sunday from July to August 2025 before being collected into a single volume.