FOR once it seemed Aberdeen's Jumbo floating restaurant might have met its match. It was here the invading army of Japanese sumo wrestlers started their day with breakfast. After dim sum, some of the 40 riskishi - who are in Hongkong for a two-day tournament - took to the streets of Kowloon wearing their kimonos and wooden clogs. Considered divine heroes by their countrymen, Hongkong residents seemed more interested in their size than their legendary sporting talent. A shopping spree in Kowloon followed breakfast. But the highlight of the day for the wrestlers was undoubtedly a special lunch at the Kowloon Shangri-La, hosted by about 100 Japanese air hostesses from Cathay Pacific. Some of the stewardesses appeared close to passing out from the excitement of meeting the overweight idols. ''These are the heroes of Japan,'' one stewardess sighed lovingly. ''What kind of ladies do you like,'' asked the woman on the podium. ''Ones who are very kind, very gentle, very sweet, and have big breasts,'' replied Kasugafuji. The only person keeping a wary eye on the proceedings was a hotel representative. One of his banqueting chairs the previous night had suffered the indignity of collapsing under a wrestler's weight. In the evening, before the tournament began in the circular clay ring at Hongkong Coliseum, the sumos challenged about 30 boys, aged between six and 10, from various schools in Hongkong, to wrestling matches. Supreme among these human mountains is Akebono, whose real name is Chad Rowan, a native of Hawaii and the first foreigner to reached the level of yokozuna, or grand champion. Miss Annette Hirate, a Japanese air hostess who served the newly crowned champion on the flight from Tokyo, said: ''He has a sense of humour. I offered him an extension seat belt but he declined because he said he was too skinny. When I offered him wine he said he didn't believe in under-age drinking.'' Miss Hirate did reveal, however, that Akebono was not seen entering the toilet throughout the four-hour, 40-minute flight, suggesting the cabin may well have been too small.