Inoha struck in the 90th minute at a nearly-full Al Gharafa Stadium to keep alive Japan's bid for a fourth continental title and crush Qatar's dreams of a first semi-final appearance. Sebastian Suria's 12th-minute opener for Qatar was cancelled out by Shinji Kagawa, who drew Japan level again with 20 minutes to go after Fabio Cesar's free-kick crept inside Japan goalkeeper Eiji Kawashima's near post.
Japan defender Maya Yoshida was harshly dismissed after receiving a second yellow card in the incident that led to the free-kick, but with the arena set for extra time, Inoha struck a decisive last-gasp blow. Japan will play the winners of tomorrow's quarter-final between Iran and Korea Republic for a place in the final.
"With 10 men, we were one man short, but we still had more possession," said Zaccheroni. That our defender scored the winning goal demonstrated what Japanese football is about."
Japan will play the winners of Saturday's quarter-final between Iran and South Korea for a place in the final.
"The players really caused problems for Japan. Not everyone can do that. It's the best performance they've given," said Qatar coach Bruno Metsu. The team put in a very good performance, tactically and physically, and showed a great image of football in Qatar. The players are disappointed, some of them cried. To lose a match like that is cruel, but that's part of the game."
Japan thrashed fellow three-time champions Saudi Arabia 5-0 in their final group game and a number of robust Qatari challenges in the early stages bore testament to the hosts' desire to impose themselves. Qatar midfielder Mesaad Ali went close twice within a minute, working Kawashima at his near post and then forcing the goalkeeper into a one-handed save with a precise drive from 30 yards.
The breakthrough came soon after, as Uruguayan-born Suria cantered onto a ball over the top and, with the Japan defence claiming offside, stepped inside Yoshida before squeezing a left-foot shot beneath Kawashima. Coach Alberto Zaccheroni led the protests from the Japanese bench, but replays showed that Suria had been played onside by Inoha.
Japan's response was slow in coming but on 28 minutes they levelled, Keisuke Honda lifting the ball over the Qatari defence for Shinji Okazaki, whose goal-bound lob was headed in on the line by Kagawa. Japan captain Makoto Hasebe stung Qasem Burhan's gloves with a low drive and Kagawa half-volleyed wide as the Blue Samurai belatedly found their rhythm in the minutes preceding half-time.
Okazaki glanced a header fractionally wide of the far post from Yuto Nagotomo's left-wing cross early in the second period, before Yoshida's harsh red card shifted the momentum in Qatar's favour. Booked earlier, the centre-back was unfortunate to receive another caution after an innocuous tangle with Yusef Ahmed.
Worse was to follow moments later for Japan, as from the subsequent free-kick, substitute Cesar curled in a tame low shot that Kawashima fumbled into the net at his near post. Japan refused to be cowed by the twin setback, however, and Kagawa levelled in the 70th minute with a cool finish inside the left-hand post.
Suria found the side-netting five minutes from full-time, tricking half the crowd into thinking he had scored the winner, before Inoha rolled home into an empty net after Kagawa had been felled by Khaled Muftah.