Manchester United's summer signing scored the winner in a 1-0 upset over France in Paris on Friday, Japan's first victory over Les Bleus in six meetings.
However, Kagawa demanded Japan sharpen up as they look to use Tuesday's game against the 2014 World Cup hosts to prepare for a qualifier in Oman on November 14.
"When you play against the best teams you need to take more risks," the 23-year-old told Japanese media on Monday. "We still don't take enough risks.
"We've got to rise to the challenge of the top teams. Not just me and [Inter Milan defender] Yuto Nagatomo on the left - we have to be linking play from the back too."
The Blue Samurai have never beaten the Brazilians in eight meetings, losing 4-1 the last time they played at the 2006 World Cup with Brazil great Zico as coach.
Current coach Alberto Zaccheroni will be able to bring back playmaker Keisuke Honda, who cut a dejected figure on the bench nursing a bruised calf in Paris.
The bleached-blond midfielder trained on Sunday after picking up the knock while playing for his club CSKA Moscow before the international break.
"We've come a long way as a team," said Zaccheroni, who took over as Japan coach after the 2010 World Cup and led them to a record fourth Asian Cup in 2011.
"We have become a very balanced side but the point of this trip is to test ourselves against the world's top teams," added the Italian.
"We're usually in control in Asia and teams sit back and try to hit us on the break. France and Brazil are not like that."
Kagawa scored a late winner for Japan in Paris to add respectability to a poor record of four defeats and one draw in their five previous games against France.
"Brazil are a stronger team than France so it should be a real challenge," said Kagawa, who has impressed at Old Trafford since his summer move from Borussia Dortmund.
"We've said we want to reach the quarter-finals of the next World Cup. In that case we have got two years to improve in a lot of areas, and we need to learn to play with more confidence. We are capable of playing a lot better."
Japan, who have played at every World Cup since first appearing in 1998, have 10 points after four matches in the final round of Asian qualifying for 2014.
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