Coomes and Buckland, who finished eighth at the NHK Trophy in 2010, were awarded 46.72 for their short dance to rank sixth out of the eight competing pairs.
And they could easily move up after the free dance with Japanese pair Cathy and Chris Reed fifth with 48.33 and Canadian's Nicole Orford and Thomas Williams fourth with 49.76.
Olympic silver medallists Meryl Davis and Charlie White are the clear favourites for the ice dance title and their second Grand Prix victory this season after scoring 69.86 in Japan.
Davis and White won Skate America last month and are well clear of fellow Americans Maia and Alex Shibutani, who were awarded 60.84 for second, while Russians Elena Ilinykh and Nikita Katsalapov are third.
Meanwhile Hanyu, who won bronze at the World Championships earlier this year, leads the men's event after improving his own world record in the short program.
The 17-year-old hit all of his jumps to score 95.32, bettering his previous mark of 95.07 set at Skate America, while Japanese teammate Daisuke Takahashi ranked second with 87.47.
Spain's Javier Fernandez was third after scoring 86.23 and Hanyu, who was to take silver at Skate America behind Takahiko Kozuka, admitted it is his current consistency that is pleasing him the most,
"I performed very well," said Hanyu. "It's very satisfying to show these kinds of results for two competitions in a row.
"I felt good with all the jumps. I feel much more satisfied than at my last Grand Prix because I could prove that it was not a fluke when I scored so much for the first time.
"I have trained harder still since Skate America where I made no mistakes [in the short program]. I had confidence and I skated cautiously where I needed to."
And there was even more for the Japanese crowd to shout about in the women's event as two-time world champion Mao Asada scored 67.95 from her short program to lead overall.
The 22-year-old has more than a six-point cushion over American Mirai Nagasu in second while the margins from Zijun Li of China in third and Georgia's Elene Gedevanishvili in sixth are much finer.
Li scored 59.62 for her short program while Russian Ksenia Makarova scored 58.93 for fourth ahead of Asada's Japanese teammate Akiko Suzuki in fifth with 58.60 and Gedevanishvili in sixth with 57.50.