The 53-year-old stuck largely to the script with his selection and promised his Blue Samurai would get under the skin of their group rivals in South Africa.
"Japan are like a swarm of feasting flies," Okada told reporters, adding that the tournament would be his swan song as national coach.
"It is work rate and organisation that symbolises my team. For Japan to win games at the World Cup we need to be tenacious and aggressive."
The only real surprise was a recall for veteran goalkeeper Yoshikatsu Kawaguchi, who has recovered from a serious leg injury in time to make his fourth World Cup squad.
"Kawaguchi brings experience as an ex-captain and his presence and leadership will be a boost," said Okada, who drew gasps when he read out the keeper's name.
He rejected the latest opportunity to back away from his target of a semi-final place in South Africa and said that he was unlikely to carry on as coach after the tournament.
"I'm not changing my objectives," said a stone-faced Okada, despite facing ridicule for not retracting his bold public target following some abject recent performances.
"I believe these 23 players can achieve those goals. This is a squad selected with that in mind.
"There probably will not be a job for me after the World Cup but right now all I am focused on is the tournament."
NO BOMBSHELLS
There were no major bombshells from Okada despite concerns over the form of playmaker Shunsuke Nakamura since his return to the J-League from Spain earlier this year.
Japan play Cameroon, the Netherlands and Denmark in Group E at the World Cup, which begins on June 11.
One of the quickest to name their squad, the Japanese are widely expected to be one of the earliest teams booking flights home, for all of Okada's bluster.
European-based midfielders Keisuke Honda, Makoto Hasebe and Daisuke Matsui carry much of the burden for Japan, who have never won a World Cup game on foreign soil.
"Honda is a big weapon for us," said Okada, who was Japan coach when the country made their first World Cup appearance - and lost all three games - in 1998.
"He scores goals and creates lots of scoring chances for us. He's become a very important player."
Okada added: "Step one is to beat Cameroon. We all know Holland are one of the world's top sides but we believe we can take points off them too."
Japan squad
Goalkeepers - Seigo Narazaki (Nagoya Grampus), Eiji Kawashima (Kawasaki Frontale), Yoshikatsu Kawaguchi (Jubilo Iwata)
Defenders - Yuji Nakazawa (Yokohama F-Marinos), Tulio (Nagoya Grampus), Yasuyuki Konno (FC Tokyo), Daiki Iwamasa (Kashima Antlers), Yuichi Komano (Jubilo Iwata), Yuto Nagatomo (FC Tokyo), Atsuto Uchida (Kashima Antlers)
Midfielders - Shunsuke Nakamura (Yokohama F-Marinos), Yasuhito Endo (Gamba Osaka), Kengo Nakamura (Kawasaki Frontale), Junichi Inamoto (Kawasaki Frontale), Yuki Abe (Urawa Reds), Makoto Hasebe (VfL Wolfsburg), Keisuke Honda (CSKA Moscow), Daisu
