Thirty-one Japanese swimmers including Reiko Nakamura and Yuko Nakanashi, both bronze medalists in Athens, will dive into the Beijing pool.
Koji Ueno, head coach of the Japanese swim team, said three medals would be acceptable though Japan won eight four years ago.
"World records have changed hands in the past weeks," said Ueno. "The competition will be more difficult in August."
Women's marathon is expected to be a breakthrough for Japan in track and field. Mizuki Noguchi, winner at Athens, is aiming to become the first ever back-to-back Olympic winner in the women's marathon.
Naoko Takahashi, winner at Sydney 2000, failed to make it to the national team. Reiko Tosa, 32, will be Noguchi's teammate. Tosa won bronze at the 2007 world championships at Osaka, Japan.
Hammer throw gold medalist Koji Murofushi is the first choice but he is also in doubt as he only finished sixth at the 2007 world championships.
Four women wrestlers notched up two golds, one silver and one bronze in Athens when the sport made its Olympic debut. Saori Yoshida, Kaori Icho, Chiharu Icho and Kyoko Hamaguchi, the four Beijing-bound wrestlers, have combined to win 17 world championship titles.
But the Fantastic Four are not always unbeatable. Yoshida suffered her first defeat in 120 matches over seven years to American Marcie van Dusen during January's World Cup. Hamaguchi lost to Wang Xu in the Athens Olympic semis, to whom she had never lost.
"We are targeting at least 10 gold medals and more than 30 medals," said Tomiaki Fukuda, Japanese chef-de-mission. "It might be hard to achieve these marks but we need to aim high."
Thirty-seven medals, including 16 golds, left Japan fifth in the Athens medal tally, behind the United States, China, Russia and Australia.
The 37 medals topped Japan's previous record of 32 registered at the boycott-marred Los Angeles Games in 1984.
If Japan can't beat its own Athens record in Beijing, it loves to see itself over South Korea on the medal standings.
South Korea, Japan's archrival in almost everything, finished ninth with nine golds in the 2004 Games.
(Xinhua News Agency July 14, 2008)