Short answers, pulled from the story.
Dentsu is Japan's largest advertising agency and the fifth largest advertising agency network in the world by worldwide revenues. It handles roughly 28 percent of Japan's entire national advertising budget, giving it a market share more than double that of its nearest rivals, Hakuhodo and ADK.
Dentsu traces its origins to two predecessor organizations that merged in 1907 to combine advertising and communications operations. The company operated under the name Japan Telegraphic Communication Co., Ltd. until 1955, when it adopted the Dentsu name.
Matsuri Takahashi, a 24-year-old University of Tokyo graduate employed at Dentsu, died by suicide in December 2015 after the company was found to have exceeded its own 70-hour monthly overtime limit. The Japanese government classified her death as karoshi, meaning death from overwork. Dentsu was convicted in October 2017 and paid a fine of 500,000 yen.
Dentsu agreed on the 12th of July 2012 to acquire British-based Aegis Group plc in a cash deal worth $4.9 billion. The acquisition closed in March 2013 and gave Dentsu a global media network operating outside Japan.
In February 2023, Japan's competition regulator filed criminal complaints against Dentsu and five other firms for alleged bid rigging of contracts for the 2020 Summer Olympics. Dentsu admitted liability. A former Dentsu executive who joined the Tokyo 2020 organising committee board was separately reported to have received more than US $8 million from the Tokyo bid committee.
The Dentsu Building is a 48-floor skyscraper in Shiodome, Minato, Tokyo, standing 213.34 meters tall and ranked as the eleventh-tallest building in Tokyo. It was designed by French architect Jean Nouvel and completed in 2002, built on the site of Tokyo's first railway station.