Following the First World War, the status of women changed. The women who had stayed behind to work in the factories wanted to maintain their status as workers. They fought for better positions, for equal pay and for legislative advances. Shortly after the Great Kantō earthquake, the United States offered economic aid to Japan. This was accompanied by the entry of many American cultural products to the island. The Japanese women of the city, found in Western fashion the affirmation of their independence. The newly rebuilt Tokyo will know many avant-garde cultural movements, affirming its modernity. The exposure to a new fashion, to a diversification of arts, to another music (jazz) encouraged the emancipation of the woman in the traditional Japanese society.
Thus is created the Modan Gāru (moga), a new, independent, modern woman, following international fashion. She is breaking with the austere and submissive traditional female model. Moga is characterized by its appearance, borrowing the western codes of the time. She adopts a boyish look, has a squared cut, wears short dresses and even more provocative: the swimsuit. Sport (especially motor sports) became the proof of assertiveness, proving emotional and financial independence. The main sources of inspiration were Western films, magazines and products, available in quantity in the major Japanese cities. The modern girl also makes possible a new lifestyle: that of the woman who smokes, drinks, sometimes accompanied by her Modan Boy (Mobo). As she was the model consumer, she could be found on the cover of magazines, in the cinema, in makeup advertisings,  but also in literature, notably by Junichiro Tanizaki.

Although very influential, especially in the cities, the moga era lasted less than 15 years. Following the Great Depression, Western influence diminished in Japan. In 1936, the authorities imposed on society the ideal and traditional image of the housewife, and this was the end of moga fashion and culture.