Fashion designer Hiroko Koshino was born on January 15, 1937, in Kishiwada City, Osaka Prefecture. Her mother, Ayako Koshino, her sisters, Junko and Michiko Koshino, and her daughter, Yuma Koshino, are all fashion designers. After graduating from high school, she moved to Tokyo and enrolled in Bunka Fashion College. While there, she won first place in the N.D.C. Design Competition. In 1961, she served as the exclusive designer for the young women's section of the Ginza Komatsu Store (now Ginza Komatsu) and also founded her own brand. In 1964, she opened an haute couture atelier in Shinsaibashi, Osaka, and has been participating in Tokyo Collections since 1977. In 1978, she became the first Japanese to participate in the Rome haute couture collection "Alta Moda," marking a sensational debut that included a feature in "Harper's Bazaar" magazine. He has participated in the Paris Ready-to-Wear Collection since 1982, and in 1984 became the first Japanese person to present a collection in Shanghai, China. In addition to his own brand, he has also designed high school uniforms and uniforms for professional baseball teams.

Having studied art as a student, he is also active as an artist. He works on calligraphy and paintings, and regularly holds solo exhibitions. In September 2012, he opened the art gallery "KH Gallery" on Namiki-dori in Ginza. Currently, until February 23rd, he is holding an exhibition in collaboration with contemporary artist Aki Kuroda, "Aki Kuroda 'Cosmo Garden' + Hiroko Koshino."