Japan took a valuable point from their entertaining opening 2-2 Group F stalemate against the Netherlands, but Moriyasu said his players were not satisfied with a draw as they prepare for a Tunisia side trying to recover from a 5-1 defeat by Sweden.
"The Netherlands played very well, and so did our team, but we are not completely satisfied," Moriyasu told reporters on Friday. "Therefore, for the match against Tunisia, I believe everyone is convinced that we need to win."
Tunisia have changed coach since the thrashing by Sweden, with Herve Renard taking charge after fellow Frenchman Sabri Lamouchi was sacked, and Moriyasu said Japan were preparing for a different opponent.
"I'm sure that the team is different from the team that went against Sweden. The new head coach is definitely firing up the players," Moriyasu added, saying Tunisia had individual quality and a solid defensive structure that could test his side.
"They do have solid defence, and they look into the gaps in the opponents so that they could tie that into a scoring position."
Japan's first match was played in Dallas, where Moriyasu said the air conditioning in the stadium was noticeable, but Monterrey presents a very different challenge.
"Here, the environment is very different. It is hotter here. And so for the players, it would be a more difficult environment," he said, adding that Japan had anticipated the weather conditions and trained to deal with them.
Saturday's match will also carry historical significance, with Japan and Tunisia contesting the 1,000th World Cup game.
"We want to make sure that it is a brilliant game which is going to be worthy of being the 1,000th game of the World Cup," Moriyasu said.
The coach was also asked about the Japanese tradition of fans and players cleaning stadiums and dressing rooms, which has drawn global attention at major tournaments.
"Many Japanese know that they want to leave the place in a better state than before," he said.
"Always helping each other, doing something together, working together. That's something that the Japanese do."
FIFA World Cup 2026
The 2026 World Cup is taking place from June 11th to July 19th in the United States, Canada and Mexico. The tournament features 48 national teams and is played at 16 modern stadiums.
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