Allegations of corruption in Olympic sponsorships involving former Dentsu director Haruyuki Takahashi have put the firm's overwhelming grip on Japan's sports marketing sector in the spotlight.
Through its role as the exclusive agent, Dentsu secured a record of around ¥370 billion ($2.8 billion based on current exchange rates) in marketing revenue for the Tokyo Organising Committee of the Olympic and Paralympic Games, a committee upon which Takahashi was an executive.
Prosecutors are now investigating Takahashi and the suspicious flow of funds from Aoki Holdings to his company. Aoki was one of the official Olympic sponsors Dentsu secured after being announced as the Tokyo Games' exclusive marketing agent in April 2014.