Japan in 2019, on the brink of a fresh epoch. Out of nowhere, a portal to another realm opens overhead, unveiling an alternate nation called Shinkoku Nippon where the heavens and ground are inverted. This twin world preserves its old militaristic stance, living in an Eternal Showa period. Their forces storm the actual Japan using colossal humanoid machines named Garann and chemical weapons called Genmu, making our contemporary armaments useless. Shinkoku Nippon immediately takes control of the government and effectively conquers Japan, ushering in the Reiwa age for the nation today.
