"We didn't think it would go as smoothly as this but the players have put in a lot of effort," said Kamada, who plays his club football with English side Crystal Palace.

"We know this isn't normal and we had a lot of trouble qualifying last time. We're relieved and happy."

Australia's 5-1 home win over Indonesia earlier in the evening meant Japan would have clinched their place even with a draw.

But Kamada made sure they did it in style in front of an expectant crowd of just under 60,000.

He latched onto Takefusa Kubo's reverse pass and dispatched the ball past Bahrain goalkeeper Ebrahim Lutfalla in the 66th minute, having come on as a substitute three minutes earlier.

Real Sociedad's Kubo then added some gloss to the night with a left-footed shot from a tight angle in the 87th minute.

Kubo was glad Japan were able to seal an eighth consecutive appearance at the Finals in front of their fans. 

"I'm relieved that we could qualify at home in front of our supporters," said Kubo, before he and his teammates addressed fans at Saitama Stadium and doused head coach Hajime Moriyasu with water.

"This here is not our goal - we want to compete against strong teams at the World Cup."

Moriyasu was forced to tinker after a difficult first half which saw Bahrain limiting Japan’s chances. 

"It was a difficult game but we knew that if we could tough it out then things would start to turn for us," said Moriyasu.

"We made some adjustments in the second half and the players continued to work hard."

Bahrain head coach Dragan Talajic vowed that his side would continue pushing to realise their dream of qualifying for the FIFA World Cup for the first time, with the defeat leaving them fifth in the standings with six points.

"I congratulate the Japanese team for their qualification but I am proud of what my players showed.

"We played a well-disciplined match against a world-class team and we will work hard in the remaining matches to accompany Japan to the World Cup," said Talajic, whose side play Indonesia on Tuesday.