Georgia denied Eddie Jones his first win of his second stint as Japan head coach after scoring a late try to claim a 25-23 victory in Sendai on Saturday.
The feisty Australian was leading Japan out for the second time, after suffering a thrashing at the hands of his former team England in Tokyo three weeks ago.
Japan were reduced to 14 men midway through the first half but fought back and led until Giorgi Javakhia's try with six minutes left gave Georgia an easy conversion to win the game.
Jones will have another chance to get off the mark when Japan play Italy in Sapporo in a week's time.
"We played the way Japan are known for and I'm proud of the team, but we're not satisfied with the result," said Japan captain Michael Leitch.
"We're looking ahead to the Italy game and we want to prepare well for that."
Jones has said he wants Japan to play the fastest rugby in the world and they came roaring out of the blocks to score a try in the third minute through Jone Naikabula.
But Japan had to play threequarters of the match with 14 players after loose forward Kanji Shimokawa was yellow carded for dangerous play after 18 minutes, then saw it upgraded to red after a review.
"We tried to stay positive," said Leitch.
"Just because you're playing with a man less, it doesn't mean you're going to lose."
Georgia took advantage when hooker Vano Karkadze went over for a try less than a minute later.
Scrum-half Mikheil Alania broke through for Georgia's second try to leave Japan with an uphill battle in the second half.
The home side dominated after the break despite their numerical disadvantage, and retook the lead when Tomoki Osada touched down for a try after a period of sustained pressure.
Javakhia had the final word when he barged over to tie the game 23-23, and Luka Matkava's simple conversion gave Georgia the win a week after they lost at home to Fiji.