Koshino studied under Masao Hara, the master of fashion drawing. She opened an haute couture atelier in Shinsaibashi, Osaka in 1964 and has participated in Tokyo Collection every year from 1977 to the present. In 1978, she was the first Japanese artist to have works shown in the Alta Moda in Rome. For 10 years starting in 1982 and for two years starting in 2009, she participated in the Prête-à-Porter collection in Paris. In recent years, she has taken the opportunity to present her works as an artist in Japan and abroad, and opened KH Gallery Ashiya in 2013.