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.

The franchise's story centers on wizards who gather mazica in order to save the world. Junior high school student Kezuru wakes up after a strange dream featuring himself as a wizard, a creature called "mazin," and a mysterious girl. The next day, his friend Kuracchi proudly shows off the newly launched Mazica Party card game. To Kezuru's shock, all the characters drawn in the game's cards are just like the ones in his dream. Meanwhile, Kezuru receives a notification for an event at the major international company Mazica. Intrigued, Kezuru goes to the Mazica Store as directed, only to meet the Mazica CEO himself, Jeff Johns. Johns says, "I have great expectations for you," and hands Kezuru Mazica Gear. On his way back home, Kezuru is attacked by an airship-like creature. Just when he thinks, "this is it!" to himself, his Mazica Gear erupts and a magic book appears. When he scratches a card, he seals a contract with Barunya, a "mazin" creature that is an odd remixed fusion between an airship and a cat. The mysterious girl Anya says Kezuru and those of his ilk will be "the true wizards who save the world." Amid all these mysterious revelations, Kezuru enrolls in the Mazica Academy and engages in Mazica Party card battles alongside his partner mazin. (Source: ANN)

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 stage is Shibuya. When Ryuuhei Oda was in elementary school, he admired his kind older brother. Ryuuhei, who witnessed the mysterious death of his brother, is now a cheerful high schooler who doesn't let the lurking nightmare surrounding faze him. One day, while kickboxing, he's bitten by a mysterious creature named Tris and has an unusual dream. He confronts his twisted desires as rumored "Drops" fly through the streets. What does he see beyond that? (Source: MAL News)