Based on the second trailer, the first arc will be an answer arc to Onidamashi-hen, with Mamiya Rina making her appearance in the sequel series. Sotsu continues the story of Higurashi no Naku Koro ni Gou, following Satoko Houjou as she attempts to stop Rika Furude from leaving Hinamizawa.

In the year 2061 AD, Japan has lost its sovereignty. The Japanese people spend their days as oppressed citizens after being divided and ruled by the four major trade factions. The country became the forefront of the world following the deployment of AMAIM—a humanoid special mobile weapon—by each economic bloc. One day, Amou Shiiba, a boy who loves machines, meets Gai, an autonomous thinking A.I. The encounter leads Amou to cast himself into the battle to reclaim Japan, piloting the AMAIM Kenbu that he built himself.

The first astronaut in human history was a vampire girl. Following the end of World War II, the world-dividing superpowers, Federal Republic of Zirnitra in the East and United Kingdom of Arnack in the West, turned their territorial ambitions toward space. Both countries have been competing fiercely for development. East history 1960. Gergiev, the chief leader of the Republic, announces the manned space flight program Project Mechtat (Dream), which, if successful, would be the first feat for humankind. At that time, Lev Leps, a substitute astronaut candidate, is ordered to perform a top secret mission. The "Nosferatu Project"—a program that experiments with vampires prior to manned missions—will use Irina Luminesk as a test subject, and Lev is to monitor and train her. Even while trifled by the walls of the race and ego of the nations, Lev and Irina share a genuine sentiment as they aim for the universe. (Source: MAL News)

Miko is a typical high school student whose life turns upside down when she suddenly starts to see gruesome and hideous monsters. Despite being completely terrified, Miko carries on with her daily life, pretending not to notice the horrors that surround her. She must endure the fear in order to keep herself and her friend Hana out of danger, even if that means coming face to face with the absolute worst. Blending both comedy and horror, Mieruko-chan tells the story of a girl who tries to deal with the paranormal by acting indifferent toward it. [Written by MAL Rewrite]