DELEGATES from Japan, France, Switzerland, the US, China and Korea, as well as the chairman of Hongkong's Urban Council, Dr Ronald Leung Ding-bong, have come to Kobe, 390 kilometres southwest of Tokyo, to literally sit and think about toilet culture. ''I'm interested in toilets and the Japanese are the leaders in this field,'' said Dr Leung, at the International Toilet Symposium which opened on Friday. His main purpose in attending was to take part in a seminar on public toilets and urban amenities, although he is hoping also to learn how to improve the territory's 300 public conveniences. ''The issue of public toilets in Hongkong is important because of the old design. Not much attention is paid to the requirements of a good, clean comfortable toilet,'' he said. Participants have been debating the issue put forward in numerous papers such as ''The History and Culture of Toilets in Europe'', ''Our Changing Cities and Lifestyles in the Context of the Toilet'' and the keynote address, ''From Taboo to Truth: Development of a Comprehensive Toilet Science'', by Professor Nishioka Hideo, president of the Japan Toilet Association. Later today, delegates will be taken on a tour of public lavatory facilities around Kobe. As a concessionary port which quickly assimilated Western influences - including the water closet - Kobe is an appropriate venue. But now, predictably, the Japanese have left the West far behind in toilet technology. With the exception of the rail network, Japan has eschewed the traditional Oriental squat loo for the pampering pleasures of the ''intelligent toilet''. These thrones, with names such as Neorest or Queen, offer the human posterior equivalent of a valet carwash. The $28,500 top-of-the-line model performs 13 functions. But the lavatorial legacy Dr Leung will pass on to Hongkong is more modest despite a budget of $14 million. ''We have done a great deal of deliberation on this and decided on the squatting type because we encountered a lot of problems with the sitting type,'' he said. ''People don't like to sit where someone else sat before, so they tend to squat on the seat, and very quickly it gets dirty or even broken.''