On an afternoon when temperatures soared past 36C shortly after the 1pm WST kick-off, Taiwan had just 9.3 per cent possession in the first half but still managed to enter the break locked at 0-0.
The deadlock was finally broken in the 61st minute via Momoko Tanikawa, while substitute Kiko Seike secured the win with a 92nd-minute header in front of 1223 fans at HBF Park.
World No.8 Japan are expected to easily top Group C, leaving Taiwan, India and Vietnam to scrap for second spot.
But as the clock ticked past 60 minutes on Wednesday and with the scoreboard still 0-0, Japan's players were worried.
Taiwan's tactics were easy to decipher; sit back and defend with gusto, and launch the ball forward - often straight back to Japanese players - whenever possession was won.
Such was Taiwan's struggles to even get the ball past halfway, their first touch in their attacking box didn't arrive until the 37th minute.
Japan continued to threaten early in the second half and they finally were rewarded when Tanikawa expertly chested down a floating pass before poking the ball into the net.
The points were secured in stoppage time when Seike charged in to head home from close range.
Japan ended the match with 89.5 per cent possession and a whopping 30 shots to zero count.
Their campaign resumes on Saturday night when they face India at HBF Park.
"It's difficult for anyone when a team is parking the bus in front of the goal - there is not much room to shoot the ball in," Japan coach Nils Nielsen said.
"But at least we know they're not going to score because they don't come up on our half, so that's one worry less.
"We need to be a bit more sharp (in attack). But this was the first game, and now we are in the tournament and opened it with three points, so you cannot be unhappy with that."
Taiwan, who take on Vietnam on Saturday, lost Hsin-Hui Pu in the 25th minute to what looked like a serious injury to her left knee after being stretchered off for medical assistance.
19°C