Robin Sena arrives at the STN-J's Raven's Flat office in Tokyo a little earlier than expected, and is mistaken for "one of Amon's girls", so is told to go away. The STN-J's witch hunting team discuss the previous night's hunt and capture of Kent Nishihama who, under interrogation, had claimed to have acquired his power from his friend Yugi Higashi. The witch hunting team set out again to the warehouse where Higashi has been hiding out. Meanwhile Takuma Zaizen and Yurika Dojima go and get Robin, who has been waiting patiently in Harry's cafe/bar, and take her to join the rest of the team at the warehouse. They arrive just as Higashi is getting the better of Amon. Robin has the opportunity to demonstrate her pyrokinetic abilities, allowing the team to capture Higashi. The team thanks Robin for her help, except for Amon who simply asks if Robin could "use her power more efficiently". Robin is surprised at the policy of capturing witches, but Miho Karasuma explains that the STN-J consider it "more humane" than killing them. Back at the office, Karasuma welcomes Robin to the STN-J.

When the bodies of mummified witches begin to turn up left and right, the STN-J team finds itself facing a serial murderer, who seems to be active every 40 years or so. But with the suspect of the earlier murders having been swept overboard at sea decades ago, who or what exactly are they facing now?