I suppose what I'm asking is: did 1920s Japan have anything like the "Roaring Twenties" of America or Europe, economically or culturally?
Usually, in discussions of Japan in the period, people refer to the "Taishō era," in reference to the regnal name of the emperor, who had some sort of neurological condition or mental disability that prevented him from exerting much influence.
The Taishō era was one in which the old guard ("Genro") of the Meiji era -- the oligarchy that had guided Japan's modernization in the Meiji period -- were dying out, with the survivors losing their influence. Although Japan had nominally been a constitutional monarchy since the constitution of 1889, real party politics didn't have much influence until the 1920s.