第 9 集: Setsuna 協助 Rinne 在冰封的地下庇護城鎮中進行一項神秘發明。
2018年8月26日 播出
In an underground shelter-city encased in ice, Setsuna meets a young girl named Rinne and begins helping her with a mysterious invention. It can apparently help save the world, but its true nature is unclear. Meanwhile, the city itself will very soon perish. (Source: Crunchyroll)