Olympic champion Andy Murray will begin his Tokyo campaign against ninth-seeded Canadian Felix Auger-Aliassime.
The Briton won back-to-back gold medals at London 2012 and Rio 2016 but has twice required hip surgery since and is currently ranked 104th in the world.
World number 15 Auger-Aliassime reached the quarter-finals at Wimbledon this month, knocking out fourth seed Alexander Zverev in the last 16.
Murray lost to the 20-year-old in straight sets at the US Open in 2020.
Former world number one Murray won consecutive matches at a Grand Slam for the first time in four years when he reached the third round at this year's Wimbledon.
Murray will also play in the men's doubles alongside Joe Salisbury. The pair face French second seeds Pierre-Hugues Herbert and Nicolas Mahut.
Brother Jamie Murray and compatriot Neal Skupski take on Argentina's Andres Molteni and Horacio Zeballos.
Elsewhere in the men's singles, British debutant Liam Broady plays Argentina's Francisco Cerundolo, while Heather Watson faces Germany's Anna-Lena Friedsam.
Britain's highest-ranked players Dan Evans and Johanna Konta were both forced to withdraw from the Olympics after testing positive for coronavirus.
Roger Federer, Rafael Nadal and Serena Williams are among big names not competing in Tokyo but Wimbledon champions Novak Djokovic and Ashleigh Barty are in Japan alongside home favourite Naomi Osaka.
World number one Djokovic is bidding for a 'Golden Slam' - Olympic gold and all four Grand Slams in one year - with the Serb having already triumphed at the Australian Open, French Open and Wimbledon in 2021.
He will open his campaign against Bolivian world number 139th Hugo Dellien.
Four-time Grand Slam champion Osaka, meanwhile, faces China's Zheng Saisai in the first round in the Japanese player's first match for almost two months since she withdrew from the French Open to look after her mental health.