The Cherry Blossoms now face a World Cup clash with Wales at Cardiff 's Millennium Stadium on 20 September.

Japan are the last side to qualify for Pool B, where they will also face Australia, Fiji and Canada.

Daisuke Ohata led the way for Japan, the prolific Kobe Kobelco Steelers wing claiming a hat-trick of tries.

Japan caretaker coach Osamu Ota said: "It's a relief to have qualified. Keeping them to zero points was nice.

We really put South Korea on their heels."

The winner of Saturday's game automatically qualified for the World Cup, but South Korea have a second chance to claim a France 2007 spot via a tough two-legged repechage against Tonga.

Japan booked their place in the showdown against South Korea with last week's 52-3 win over Hong Kong, the third team in the Asia triangular series, who also lost 23-5 to the Koreans.

Wales have won all six of their full Test encounters with Japan, who will be coached by former All Blacks wing John Kirwan from January, and clocked up more than 50 points on each occasion.

Those fixtures included group games at the 1995 and 1999 World Cups.

The sides last met in November 2004 at the Millennium Stadium, Wales running in 14 tries to record a 98-0 victory, their highest winning margin in a Test.

Japan's qualification was seen as crucial for the country s bid to host the 2015 World Cup after losing out to New Zealand in the race to stage the 2011 tournament.