Japan upstarts Machida advance in Asian Champions League
Machida, who were playing non-league football less than 15 years ago, went through 1-0 on aggregate after Hotaka Nakamura's first-half header made the difference.
"We were determined to make history for Machida," said Nakamura.
"It was a tough game but we have written a new page for the club. Now we move on to the next stage and we want to show everyone something great."
The Asian Champions League becomes a single-leg knock-out competition from the quarter-finals onwards, with all games set to be played in Saudi Arabia next month.
The Asian Football Confederation last week postponed last-16 matches played by clubs in the Middle East after the US and Israeli strikes on Iran.
Machida and Gangwon kicked off for the second leg of their tie at the Japanese club's homely stadium in the suburbs of Tokyo after a 0-0 draw in South Korea last week.
Machida suffered an early blow when Japan international winger Yuki Soma was forced off with an injury in the 12th minute.
His replacement Na Sang-ho supplied the cross for the winning goal in the 25th minute as Nakamura ran in at the back post to head home.