Defender Azusa Iwashimizu delivered a header from a corner kick from captain Aya Miyama in the dying seconds of extra time as Japan beat China 2-1 to book a spot in the final at the Women's Asian Cup on Thursday.
The reigning World Cup champions, who came first in Group A in the group stage and reached the final for the first time in five tournaments, are seeking their first Asian title.
"The players kept running until the end," said Japan coach Norio Sasaki. "It was their persistence to win. The cheers from fans were encouraging. We want to respond to expectations in the final."
Japan, who will face the winner of the other seminal match between Group B winner South Korea and Group A runner-up Australia, extended its unbeaten streak to eight matches against China. The final match to decide third place will be played on Sunday.
Homare Sawa scored the opening goal on a header in the second half on another perfectly placed corner kick from Miyama, but China tied it on a penalty kick as regulation drew to a close.
Japan secured its spot in next year's World Cup in Canada during the group stage in the qualifying tournament.