At the end of season 2. Yuuri defeats Shinou, but since Shinou had been defeated, Yuuri and Murata could no longer go to the Shin Makoku. However, because Yuuri had fought and defeated him, his powers had surpassed that of Shinou's, resulting in him being able to rely on his own power to return to Shin Makoku. After the ceremony at the age of 16, Yuuri slowly begins to discover that much has happened while he was away. The ten officials of the noble family have decided to make Wolfram the next Maou, but now that Yuuri has returned and taken back his role as Maou, complications arise when one noble disagrees with Yuuri returning to the throne. In addition, an ancient secret society that threatens the peace of both humans and Mazoku has risen, and a fight for the throne that now leaves the nobles wondering who is the legitimate Maou.

Due to a mysterious disease, the genius Iria Akagami has been forced by her family to stay in a mansion on the isolated Wet Crow's Feather Island with only a handful of maids. To keep herself entertained, Iria invites a variety of fellow geniuses to stay as guests in her home, including computer savant Tomo Kunagisa and her unnamed assistant, skilled fortune-teller Maki Himena, famous artist Kanami Ibuki, academic scholar Akane Sonoyama, and renowned cook Yayoi Sashirono. These visits progress as normal until one of the guests is found gruesomely murdered in the night without a single clue as to the identity of the killer or a possible motive. Tensions rise between those on the island as the killer remains at large, and Tomo's assistant takes it upon himself to uncover the culprit's identity before the murderous events progress any further.

With Major Motoko Kusanagi missing, Section 9's Batou is assigned to investigate a string of gruesome murders—seemingly at the hands of faulty gynoids, or sex robots. But when a faulty gynoid leaves Batou a cryptic message, he begins to question the cause of their malfunctions. Suspicions of politically motivated murder and an illegal "ghost" quickly crop up, drawing Batou and his partner Togusa into a perilous web of conspiracy.

As their investigation goes on, the line between man and machine continues to blur, and reality and perception become indistinguishable. Confronting strange and dangerous foes, Batou and Togusa explore a futuristic world filled with machines and living dolls but utterly devoid of humanity.

[Written by MAL Rewrite]

The second cour of Hoozuki no Reitetsu season 2.