Eddie Jones said Japan were “heading in the right direction” despite losing 52-17 to England in their first game in charge in Tokyo on Saturday.
Jones warned earlier this week that Japan would “take Britain to the last minute”, declaring he was “in a really good mood”.
Instead, an inexperienced Japanese side, which included four debutants in the starting line-up and four coming off the bench, conceded eight attempts despite scoring two in a touching finish to the game.
Jones, who led England to the World Cup final in 2019, said he had seen promising signs as he tried to instill a high-tempo style of play in his new team.
“We showed enough in attack to know we were going in the right direction, but we couldn’t capitalize on it,” the Australian said.
“Today we got eight new caps who had a fantastic learning experience. Sometimes you get a lesson before you get another one and they got it today.”
Despite the sweltering weather, Japan opened the scoring with a penalty kick and held England back on their own goal line for the first 10 minutes.
England weathered the storm and scored four tries in the first half, with flyhalf Marcus Smith making a big impact.
Jones said his team “needs to build their physical and mental capacity” to play the full 80 minutes.
“In the first 15 minutes of the game we put pressure on England. We took the game to England,” he said.
“It’s just practice. Practice hard. We will go there.”
Jones’s time with England ended on a sad note when he was sacked at the end of 2022 following a string of poor results.
The feisty 64-year-old said it was great to be reunited with his former team.
“I think it’s always a little fun when you play against a team you coached,” he said.
“It makes it a little more interesting that way. You know the players.
“Some of the young players you bring in, you want them to do well, but you don’t want them to do too well against you.”