THE long, narrow book shop appears to be in total darkness as you enter from the sunlit street in downtown Sapporo, writes Jeremy Walker. Spotting a gaijin (foreigner) in the doorway, the elderly shopkeeper pays no attention and continues reading his newspaper, leaving the visitor to fend for himself among the rows and rows of dusty, over-flowing shelves. But any attempts to find what you are looking for - in this case what has been suggested as the possible source of the J.League - prove fruitless. There is no alternative but to interrupt the shopkeeper and, slowly and clearly, to utter the magical words Captain Tsubasa. In an instant the shopkeeper is on his feet, a smile on his face and he's homing in on a stack of comic books. Captain Tsubasa was first published 10 years ago and creator Yoichi Takahashi produced 36 different stories during the comic's lucrative five-year run. It tells the adventures of a primary school boy with a passion for soccer - and the comic books stirred an interest in a young generation of readers who can now be found following the fortunes of real-life sporting heroes in the J.League. Kashima Antlers fan Fukuko Ohdoh, 21, from Ibaraki, explained: ''About 10 years ago there was a popular comic book called Captain Tsubasa and many children read it. ''Although soccer was not very popular in those days, the comic books were exciting and the stories were good, so many young people took an interest in soccer. ''Now, 10 years on, those people are in their late teens and early 20s and are the right generation for the J.League.'' Her friend, 20-year-old Michiko Kasuga, from Niigata, added: ''I think the Japanese people are very easily influenced by the mass media and a lot of young people became interested in soccer at an early age because of the comic. ''Then the J.League came along and television supported it, so it's soccer, soccer, soccer everywhere and everyone follows it. ''Most of the players are young and handsome and they attract lots of girls to the games.'' Baseball and sumo are Japan's two major spectator sports but soccer has joined them at the top. ''For me, soccer players use more power than baseball players and are more energetic. So when you are in the stadium watching a match you can feel the passion of the players more easily,'' said Antlers fan Ohdoh. Toshimasa Tsujiuchi, a 22-year-old JEF United fan from Kanagawa, believes the J.League is here to stay. ''There is so much news on the J.League in the newspapers and on TV that you can't help but take an interest,'' he said. ''Some people will lose interest but others will continue. For me soccer is fresh. ''The teams are based on towns and cities and the spectators will stick with their teams and keep the game popular.'' His opinion is not shared by 21-year-old Katsuichiyo Yamanaka from Ibaraki. ''Sumo is better to watch than soccer and both sumo and baseball are well established in Japan. There is a lot of interest in soccer now but I'll give it three years before it goes down.''