Satoshi "Sasshi" Imamiya and his childhood friend Arumi Asahina have grown up together in Osaka's Abenobashi shopping arcade, and when the neighborhood is slated for demolition, the two stumble into a crack between worlds. Pulled through a portal, they wash up in the first of a string of alternate realities that parody everything from sword-and-sorcery epics to war films and video games, each one built around some version of the arcade they know.