The men's Sevens will be played on July 26-28 and the women's on July 29-31.
Japan's men finished fourth at the 2016 Olympic Games in Rio de Janeiro, losing 14-54 to South Africa in the bronze medal game. But en route to the playoffs, they beat France and caused the shock of the tournament by beating New Zealand 14-12.
In the decade before the Games, Japan hadn't registered higher than 15th in the Sevens world rankings.
But as captain Yusaku Kuwazura told World.rugby the side utilised camaraderie and self-confidence to surprise. Now retired he still believes they could have done more.
"Our goal was to get a medal in Rio, so we prepared for that.
"We got to fourth, and so we didn't reach our goal, but everyone seems to think we did really well. But we didn't reach our goal, so we weren't that impressed. But looking back on it, I guess we did do well," he said.
"For six months, we focused on New Zealand, and worked on our strategy of how to beat New Zealand. That is probably why we beat them."
The self-belief arising from that achievement has been an inspiration for Japan's team for this year's Olympics.
"They will want to win a medal this time, of course," he said.
However, preparation and analysis were a little more difficult due to the lack of play caused by Covid-19 disruptions.
"We can't participate at the World Series, which makes it hard to predict which teams are good. Nobody can really judge who is the best right now," he said.
The Japan Sevens coach Kensuke Iwabuch believes that could be an advantage for the side.
"As a one-off tournament anything can happen, especially in Sevens. We need to peak at the Olympics," he said.
Japan are in Pool B along with Fiji, Britain and Canada.