Brazil survived a World Cup Round of 32 scare when they fought back to beat Japan 2-1 after Gabriel Martinelli squeezed in a shot at the far post deep in stoppage time.
The result dashed hopes of a team touted as dark horses who could make a long run in the tournament by beating traditional soccer heavyweights such as Brazil.
“The gap between us is closing now," Moriyasu told reporters. "Of course, Brazil are a top tier team and we are definitely approaching that level.
"As a result we were devastated. Of course, there is that kind of difference in our level and we have to up our game. To compete at the top is a goal we all have."
For at least the opening period Japan stood toe-to-toe with Brazil as defenders flew around the pitch, broke up passes and closed down space while taking a shock 1-0 into the break.
The result denied Japan a first World Cup knockout win but Moriyasu said the fact a number of players stepped in to replaced injured teammates provided a broader range of experience and boded well for the future.
"This is one of the strong points of the Japanese team," Moriyasu said. "Having more players gain such experience will contribute to the growth of football in Japan."
Improvement in different areas, including transitioning from attack and dealing with teams like Brazil able to hold possession for long periods are things Japan need to work on, Moriyasu said.
He also praised his team for their effort throughout the match against Brazil and said his players showed how dangerous they can be on the counter against top teams.
"What I said to the players is play as if we have gone back to 0-0," Moriyasu said. "Defending will lead to attack and that is something I conveyed to the players."