Gorou Joe is leading a carefree life in Gujo Hachiman, a quaint historical town situated in Gifu Prefecture. However, his routine gets altered when an elderly "water fairy" suddenly appears before him, seeking his assistance in aiding others. The fairy bestows upon Joe the power to morph into "GJ8 Man," a witty reference to the name of the town. This alludes to the fact that the kanji for the number 8 in "Hachiman" is pronounced "hachi" in Japanese.