After graduating the Keio University, Onishi joined the Isetan Mitsukoshi Holdings and served as Chief Executive Officer and President at Isetan Mitsukoshi Ltd., and the President, Chief Executive Officer and Executive Officer at Isetan Mitsukoshi Holdings Ltd. from February 2012 to March 31, 2017.
Onishi joins the Japan Airport Terminal Co., Ltd. Currently, Vice President of Japan Airport Terminal and President of Haneda Future Research Institute.