Oyama worked as an accountant at Deloitte Touche Tohmatsu LLC. He is a Certified Public Accountant and a member of the Japan Certified Public Accountants Association. He engaged in legal audits and IPO support work based on listed companies Financial Instruments and Exchange Act. He also gained experience from involvement in actual IPO’s.

In addition, he opened a company and has experienced advisory on internal control and business flow within the company. He has consulted on accounting, finance, and tax, and has been incubating early-stage companies. In 2017, he assumed the post of Managing Director of PJP Eye LTD.