The pair each won $US12,000 ($NZ18,500) for winning the signature event of the Winter Games, the snowboard halfpipe World Cup.
Katayama only qualified for the final with the ninth highest score on Friday, but dished up a spectacular first up run while the sun was still shining.
As the ninth ranked athlete, he was the second to drop into the 165m long pipe, and did not waste any time setting the standard.
His score of 90.00 was ultimately enough to win the event, and was set before heavy fog swept over Cardrona.
He started his winning run with a frontside 10 tail grab, before wowing the crowd with a flawless cab double 10, a frontside 9 tail grab, a backside 9 mute and a frontside 10 double mute grab.
''I am very happy to get the win,'' the 20 year old said.
''This is just a start - my first win in a World Cup. I want to be on the podium a lot more in the future. The conditions were getting softer. It was a little bit hard to ride but I still enjoyed it very much.''
Fellow countryman Taku Hiraoka, who managed a 37.75 and 82.50 with his first two runs, came agonisingly close to hitting the front with his final run, but he had to settle for silver after scoring 89.00.
Top qualifier Iouri Podladtchikov, of Switzerland, gave it his all with the final run of the event, but he too came unstuck digging deep into his repertoire of moves, and had to settle for bronze.
More than half the 10 strong field fell in the third and final run in pursuit of the gold medal.
Xuetong, who won silver at the Winter Games two years ago, and gold in 2011, did enough in her first run to win the women's event. She qualified second for the final behind American Kelly Clark, and broke out an air to fakie backside grab, a cab 7 backside, a front 5 backside grab, a back 5 mute and a front 7 indy to score 88.00.
Clark, the most dominant woman snowboarder in the world, and winner of the ESPY award for best female action sports athlete last month, failed to fire in the final.
She came unstuck in all three of her runs to finish at the bottom in the field of six.
Switzerland's Andri Ragettli and Germany's Lisa Zimmermann won the men's and women's freeski big air finals yesterday.
Ragettli, who qualified in 10th last week, earned an unbeatable 180.25 points after landing a left double misty 12 tail grab and a left triple cork 1440 high mute. Zimmermann scored 176.75 with a left 5 Japan grab and a switch left 5 safety grab.
Japanese athletes Keita Inamura and Miyabi Onitsuka won gold in the men's and women's snowboard big air finals. Inamura scored 160.66 with two huge jumps, while Onitsuka scored 152.99 in a run that included a back 7 front 3.
Kiwi Andy Pohl made up for his fourth place finish in the cross country mass start event on Saturday by winning silver in the individual start event at Snow Farm yesterday. Pohl, who hails from Dunedin and is now the general manager of Snow Farm, completed the 10km race in 28min 06sec, just 11sec behind winner Seong Beom Park, of Korea.
Slovenian Barbara Jexersek won gold in the women's 5km race in 14min 43sec. She outpaced Korea's Chae Won Lee, the winner of Saturday's mass start race, by 14sec.
Slovakian Adam Zampa won his second gold in as many days at Coronet Peak yesterday. After winning gold in the alpine slalom on Saturday, he won the giant slalom in 1min 46.49sec yesterday.
He plans to come back in two years and defend his titles. In the women's event, Austrian Chiara Mair, who is ranked 59th in the world, won in 1min 48.89sec.
