The Japanese camp is happy with how the side has prepared but according to team manager Kang Jeong, the Tongans cannot be underestimated.
"We have had good preparation for this game," he said.
"We will do our best against Tonga.
"Tonga has big boys. I think it will be a tough game.
"I think Tonga forwards are strong," he said.
"The good point is we have good fitness."
He said the Japanese were looking forward to the clash.
Junior Japan is coached by Ryuji Nakatake and flanker Syoki Kin will be captain.