TOKYO — It’s not an official sponsor of the Olympics. It will remain invisible to the millions of viewers who begin tuning in this week. But without it, the Tokyo Games could not have happened.The force behind the Olympic curtain is Dentsu, an advertising goliath with near mythical levels of power and influence in Japan.As a gatekeeper to the world’s third-largest economy, it has become a major figure in international sports. It played a prominent role in Tokyo’s Olympic bid, then was named the Games’ exclusive advertising partner, bringing in a record-shattering $3.6 billion from Japanese sponsors. …
