Coach Eddie Jones says Japan are on the right trajectory, with the way they played against Italy and Ireland in their first two Nations Championship tests proving it was "pretty obvious".
After stunning Italy 27-10 in Tokyo a week ago, Japan took an early lead against Ireland in Newcastle on Saturday and were within six points of Andy Farrell's world No 3 side with 10 minutes left.
A converted try for Ireland on the hooter gave them a 36-20 win, and Farrell admitted the scoreline flattered his under-strength side.
"Seventy minutes it's 26-20, we're playing without our two centres, so I think it's pretty obvious that the team is competitive," said Jones, Japan's Australian coach, who returned after a four-game suspension for abusing match officials.
"They're a top-three team in the world and they do the simple things well over and over again. We had some opportunities to put ourselves in a winning position, but we weren't quite good enough.
"I'm very proud of the effort of the boys, and yeah, I think the trajectory of the team is in the right direction and the opportunity now is to take it on to France."
Japan face a major examination next weekend back on home turf against the slick Six Nations champions France, who demolished Australia 42-26 in Brisbane.
France plundered 30 unanswered second-half points with their attack proving overwhelming.
Jones's side also plays at a high tempo and their speed repeatedly stretched the Irish defence, only for handling errors to let them down.
"We played the whole first half on the back foot. We didn't stop their momentum in attack, and when you're going backwards in defence it's hard work to get forward in attack," he said.
"So at halftime we made some slight adjustments to how we're going to play, and I thought in the second half we were able to gain some good momentum and put ourselves back in with a chance of winning the game."
Ireland, who are on a six-match win streak, travel to Auckland this week and an Eden Park cauldron for a blockbuster showdown with New Zealand, who thrashed Italy 47-17.
Farrell is expected to revert to a full-strength side after awarding four debuts against Japan.
"We'll dust ourselves off going into what is an unbelievably exciting week," said Farrell.
"If you can't get excited about that, we might as well not board the plane to Auckland."