Harada has participated in numerous festivals, including in Spoleto, Kuhmo (Finland) and Los Angeles. In 1969, he founded the famous Tokyo String Quartet and for more than 12 years was the first violin of this ensemble. He toured around the world with the band and performed at music festivals in South Bank, Tanglewood, Lucerne. Being known for his talent, technique and musicality, Harada began teaching at major music training centers, including the Cleveland Conservatory.
In 1983, Harada returned to Tokyo and created several other well-known chamber music ensembles, including NADA and Mito Quartet. Since his debut as a conductor with the New Japanese Philharmonic Orchestra in 1988, Koichiro Harada has increasingly focused on this area of activity. He conducts the Philharmonic Orchestras of Osaka, Hiroshima, Kyoto, Tokyo, the Orchestra Ensemble Kanazawa, the Kyushu Symphony Orchestra and many others.
For his records, Harada received the "Stereo" and "Gramophone" Magazines Award for the Best Record of the Year. Grammy Nominee.
Harada is currently the Head of the String Instrument Department at the Toho Gakuen School of Music and the Music Director of the Ishikawa Music Academy in Japan. Koichiro Harada was invited to Juries of many major international competitions: the Queen Elizabeth Competition in Belgium, the Indianapolis Violin Competition, the N. Paganini Competition in Genova, and the Henryk Wieniawski Violin Competition in Poland. In 2005, he was the President of the Jury of the Long and Thibaud International Violin Competition in Paris.