The Blue Samurai were too quick and slick for their limited opponents, with playmaker Keisuke Honda opening the scoring early in the 3-0 win and at the centre of all that was good in front of 63,000 happy fans in Saitama on Sunday.
Forwards Ryoichi Maeda and Shinji Okazaki also scored in the easy win, with Oman failing to record a shot on target.
The victory took Japan top of Group B in the fourth round of qualifiers in Asia, with only the top two from the two five-team groups guaranteed a place in Brazil in two years time.
With Honda, Manchester United target Shinji Kagawa and Inter Milan's attacking leftback Yuto Nagatomo in flying form a fifth consecutive finals appearance looks a certainty but the team are taking nothing for granted.
"Keisuke's goal that early made it easier for us. Important, nice to win the first game but it is early days so we have got to keep winning," Kagawa said afterwards.
Although Australia are expected to join Japan in qualifying from Group B, Jordan and Iraq, who met in Amman on Sunday, have been tipped to push the Asian heavyweights close.
However, their 1-1 draw lacked the panache of the Japanese play and neither of the 2011 Asian Cup finalists will have felt too threatened by what they saw in Jordan.
Iraq took the lead early after a neat finish by Nashat Akram but they struggled to create much else and a goalkeeping gaff by Mohammed Kassid allowed the home side to grab an equaliser just before halftime.
While Jordan were gifted a goal, Uzbekistan were angry after believing they had been robbed of one against Iran.
Having wasted several good chances to take the lead against their lethargic opponents, the Uzbeks began celebrating what they thought was a 75th minute goal after Odil Akhmedov's effort appeared to cross the Iranian goalline.
After defender Seyed Hosseini cleared the ball standing behind the line, his team mates made the most of their apparent good fortune to win the game with a goal in the fourth minute of stoppage time thanks to substitute Mohammad Khalatbari.
"We scored a goal in the second half, but the referee didn't see it," Uzbekistan coach Vadim Abramov bemoaned.
"I don't know what did happen with us in the last minutes, sometimes we concede goals at the end of the match. We lost the game, but it is not a tragedy."
Iran lead Group A after their opening three points, alongside 2022 World Cup hosts Qatar who won 1-0 in Lebanon.
Sebastian Soria scored the winner but lowly Lebanon will be kicking themselves after Youssef Mohamad missed a great chance to snatch a point late on.