It was a stunning triumph for the lightweight pair who crumbled under the pressure at home last year when they stood poised to end the drought.
Leading after the third round, Maruyama and Toshimitsu made no mistake in the closing foursomes birdieing three of the first four holes to steady their nerves before going on to card a six under 66 for a 36-under total of 252.
That was two strokes better than US pair Phil Mickelson and David Toms who had moved into contention with a 15-under 57 on Saturday, but who had to settle for a 65 Sunday.
At one stage it looked as though the Japanese pair had blown it again when they took a double-bogey six at the easy 13th which put the Americans ahead for the first time.
But birdies at the 16th and 17th combined with the Americans making a mess of the last hole when Toms ran his second into an unplayable greenside hazard for a double-bogey six, opened the door again.
This time Maruyama and Izawa made no mistake, comfortably parring the 18th for the cup.
“It’s taken 45 years to take the World Cup back to Japan so obviously we are very happy,” said Izawa.
The last Japanese victors in golf’s premier multi-national team event were Torakichi Nakamura and Koichi Ono on home turf at Tokyo in 1957, succeeding Ben Hogan and Sam Snead.
The day started with Japan one ahead of Fiji with South Africa a further shot back and the United States needing to make up three.
But it quickly turned into a two-horse race with the Japanese making early birdies and the Americans moving into second spot with a birdie on the first and an eagle three on the third.
Japan reached the turn in 32 with the Americans shooting two strokes better to lie one back too set up a gripping finale over the back nine of the spectacular, jungle-fringed Vista Vallarta course.
Final round results:
252 Japan 64 64 58 66
254 United States 65 67 57 65
258 Korea 61 67 64 66, England 65 63 62 68
259 South Africa 62 64 62 71
260 Argentina 64 68 62 66, Australia 60 67 65 68
261 Ireland 64 67 62 68, Canada 59 67 64 71
262 Fiji 63 62 62 75
263 Denmark 63 70 62 68
265 Wales 63 68 65 69, Scotland 63 65 62 75
266 Sweden 62 71 64 69, Switzerland 63 67 65 71
268 Myanmar 66 66 64 72
270 New Zealand 65 73 64 68, Singapore 70 65 65 70, France 61 72 64 73, Trinidad/Tobago 63 66 64 77
271 Germany 67 69 64 71
274 Venezuela 66 67 72 69
277 Mexico 68 72 66 71, Colombia 66 68 69 74—Agencies