After the mystery of the Queen of Cats is resolved and tearful good-byes exchanged, it's time to cheer up! Former novelist and current hot-to-trot slacker Ogawa Sumireko gets dressed up in a yukata and takes her otherworldly allies Adashino Ren and Oto to see a fireworks display. But mysteries are always brewing on summer nights, and who knows who, or what, the trio will encounter in the dark between flashes of light!