"It's human nature to want more," Sawa, with a gold medal hanging from her neck, told a packed news conference at a hotel in Tokyo after the team arrived at the capital's Narita airport, thronged by 400 fans and 250 media.
The gutsy 32-year-old playmaker added: "With this gold medal in front of me, I really feel that my next goal is to grab the Olympic gold medal as we have yet to get any medal at the Olympics."
Japan, which finished fourth at the 2008 Beijing Olympics, came from behind twice to beat world-number one and twice champion the United States 3-1 on penalties in the final of the World Cup in Frankfurt.
It was the first football World Cup title for any Asian country and lifted spirits in Japan, which has been recovering from the 11 March earthquake and tsunami which left 21,000 people dead or missing and sparked a crisis at a nuclear power plant.
With its teamwork, crisp passing and never-say-die attitude more than offsetting its physical shortcomings, Japan upset host and holder Germany and Sweden on the way to glory.
"I've come a long way as a member of the Japanese national team over 18 years. I never thought I would get the gold medal," said Sawa, whose career included a stint with US side Washington Freedom.
"The Asian Olympic qualifying round will start this year with other tournaments and matches coming up soon," she said. "I want to condition myself for the battles ahead."
Asian qualifying will be held in China in September with six nations - Australia, China, Japan, Korea DPR, Korea Republic and Thailand - vying for two Olympic berths.
"We still lag behind the United States and Germany in many aspects," admitted Sawa, who won the golden boot with five goals and was named the most valuable player at Germany 2011. "We must improve individual skills much more."
Japan coach Norio Sasaki said: "We were gutted when we finished fourth in Beijing. We will really want a medal at the next London Olympics.
"We need to reinforce our basics and stay on our guard."
Both Sawa and Sasaki believe the World Cup victory will boost women's football at home, where many players are less privileged in wages and conditions than their counterparts in the west, especially the United States.
"I really think Japanese women are fit for football. I want them to feel like kicking a football because it's fun," the coach said.
Sawa added: "I want to tell children to have a dream - and never give up."