Japan will play in the 2015 World Cup after claiming the Asian Five Nations title beating Hong Kong 49-8 in Tokyo.
The Brave Blossoms ran in eight tries including a first-half hat-trick for Yoshikazu Fujita.
Despite the heavy defeat, Hong Kong will now take on Uruguay in the first round of the World Cup repechage.
Japan, who will host the 2019 World Cup, will take on South Africa, Samoa, Scotland and the United States in Pool B of next year's tournament in England.
“It was a tough old game but we have achieved our first goal, to qualify for the World Cup, which is fantastic,” said Japan head coach Eddie Jones.
“Now the next target is to reach the quarter-finals of the World Cup, so everything we do from now on is about making sure we are in a position to reach the quarter-finals.”