The nine-time Olympic gold medallist came to Japan hoping to inspire young athletes from the northeastern part of the country that was devastated by an earthquake and tsunami in March 2011.
Lewis visited Sendai and Ishinomaki with Willie Banks, the former triple jump world record-holder, and Mike Powell, who set the long jump world record at the world championships in Tokyo in 1991.
Tokyo, which hosted the 1964 Olympics, is bidding against Madrid and Istanbul for the right to host the 2020 Games. Tokyo also bid for the 2016 Olympics, which were awarded to Rio de Janeiro.
"I wish them the best of luck because I think they will put on a tremendous games," Lewis said. "I will be at the 2020 Games wherever it is, and I hope it's here."
Lewis said Japan's reputation for innovation would help the bid.
"I'm all for progress," he said. "I believe in high-technology. I believe in state-of-the art new stadiums for people. It makes it more comfortable, and leads to improved performances by the athletes.
"Japan has always been a very high-tech community and I think it will be a showcase for a stadium probably more high-tech than any stadium that's ever been made. I think it will be a great place to be."
Lewis has an affinity for Tokyo, where he said he ran "the best race of my life" in reclaiming the 100-meter world record in 9.86 seconds at the 1991 world championships.
"The fans really know sports and understand the events," he said. "And for me it was tremendous because when I came here in 1991 it was just this huge flow of energy."
Tsunekazu Takeda, head of Tokyo's Olympic bid, said Lewis' "strong endorsement of Tokyo echoes the widespread international sentiment for our bid and our goal to deliver a dynamic celebration in the heart of Japan's capital."
Lewis, Powell and Banks took part in a "Tohoku Sports Summit" which sought to bring practical support and technical advice to young athletes and coaches from the region with the goal of producing the champions of the future.
Lewis said he was moved by the experience.
"Kids were great and the energy of the people was amazing," he said. "I could see the hopes and dreams in the eyes of the kids, and the energy in their hearts. It was inspiring."
Lewis said after the devastation of the quake and tsunami, the Japanese people "came together and they have a spirit that they're going to bring it back and better than ever."
"It's been a real great visit back to Japan. And we hope some of the kids we were working with yesterday will maybe be back here in 2020."
The trio were invited to Japan by the Power of Sports project and two-time world 400-meter hurdles bronze medallist Dai Tamesue, who also participated in the coaching conference and training camp.
"Japan has always had a special place in my heart," Powell said. "Breaking the world record here changed my life."
Banks, who has had a long association with Japan, spoke about his desire to have a positive impact on a place that is close to his heart.
"I wanted to help the kids in Tohoku," the 57-year-old Banks said. "We need to give these kids hope, love and strength. This will help them rise after the disaster."