Japan manager Takeshi Okada has claimed a united squad was the secret to their qualification.
The Blue Samurai sealed their progression into the World Cup last 16 following an impressive 3-1 victory over Denmark in Rustenburg.
Japan now take on Paraguay in the second round and go into the game high on confidence after a good showing.
Okada believes his squad have an excellent spirit, which was why they overcame the Danes in the Royal Bafokeng Stadium.
"Our team has a strength that others don't have," he said.
"We are truly united. We wanted to demonstrate that football is a team sport."
Okada added that he did not want to play for the draw, even though a point could have been enough to advance, and he is now relishing the Paraguay test.
"We knew we could have made it with a draw but we did not want to be passive," he remarked.
"Denmark put us under some pressure at the start and we had some risky situations, so we changed the formation and we were able to score the two free-kicks that put us in the driving seat.
"We will enjoy this but we have not achieved our final end.
"We have to go for more, starting with what will be a first game in the knockout stages, against Paraguay.
"The players will have a break tonight and tomorrow we start working again."