Japan made it three straight bonus-point wins in this year's Asia Rugby Championship, beating South Korea 60-3 on Saturday.
The Brave Blossoms ran in 10 tries at Namdong Asiad Rugby Field, with Atsushi Sakate and Ryohei Yamanaka both bagging braces.
The win lifts Ryuji Nakatake's team to 15 points from three games and ensures it needs just a bonus point from next week's game in Tokyo against Hong Kong to wrap up the title.
"The players were really hungry to play and win and their motivation was the biggest reason for today's victory," interim coach Nakatake said.