From 2004 to 2008, Kashiwagi was Chief Investigator at the Investigation Bureau of the Japan Fair Trade Commission (JFTC), during which time he led the JFTC to victory in its fight against several companies in cases such as NIPRO (private monopolization) and Microsoft (unfair business practices, non-assertion provisions). He has also reviewed other cases such as the Marine Hose cartel case and the Qualcomm case. From 2007, he also served in the JFTC’s Merger and Acquisitions Division, was responsible for legal revisions of the prior notification system, drafted revised clauses for Chapter 4 of the Antimonopoly Act and conducted a review of BHP Billiton/Rio Tinto.
Since joining TMI in 2008, he has obtained both maximum immunities and reductions of fines imposed by various countries on Auto part cartels, been involved in numerous international cartels such as Auto shipping cartels, and has also been involved in some highly complex merger control cases, as well as numerous cases of private monopolization and unfair business practices.


In 2018, Kashiwagi founded a new law firm, KOIKE & KASHIWAGI LAW OFFICE , specialized in anti-trust, competition, compliance, risk management, M&A, litigation etc.