After the experience in audit services at an audit firm, Yoichi was involved in various tax-related practices at Grant Thornton Taiyo Tax firm, including tax compliance, handling tax audits and disputes, transfer pricing mutual agreement procedures (MAP) and advance pricing agreement (APA) , tax due diligence for acquisitions, and the development of tax governance frameworks for global companies. As a managing partner of Grant Thornton Taiyo tax firm, he was also engaged in overall firm management and participated in the operation of tax services across member firms as a member of the tax committee of its global network.