TOKYO, May 22. - A relatively obscure young athlete emerged from the shadow of a renowned stable-mate today to win the Emperor's Cup, symbolic of the championship in sumo wrestling, Japan's popular traditional sport.
    Surprising millions of avid followers of the esoteric sport, the 22-year-old Wakamisugi bettered the record of his mentor, Wakanohana, the senior yokozuna (grand champion) and perennial winner in the fifteen-day tournaments held six times a year in different Japanese cities.
    Wakamisugi, show professional name conveys that he has the strength of "three young cedar trees," came through the Tokyo series with a record of fourteen victories, one more than Wakanohana (Flower of Youth). Both belong to the Hanakago (Flower Basket) Stable, and did not wrestler each other in the tournament.
    The new champion carries 290 pounds on his 6-foot 1-inch frame, making him a giant among Japanese in general but not of exceptional size among sumo wrestlers. He had stood well below the top-class performers in the elaborate hierarchy of the sport, but now, presumably, will get a promotion.
    Sumo, a form of wrestling aid to have developed in Japan more than 2,000 years ago, pits two nearly naked contestants against each other on a raised clay ring. The loser is the first to be tossed beyond a rope boundary or to touch the floor with any part of the body except his bare feet.
    The bouts draw capacity crowds and the matches are seen on television throughout the country. Only baseball, which is played in bigger stadiums, draws more spectators.

    TOKYO, May 22 (AP) - Wakamisugi, the new Sumo wrestling champion, had to forego the customary open-car parade through downtown Tokyo tonight because of a lack of police. The police has been mobilized to guard against demonstrators opposing the United States-Japan security pact that was passed in the Lower House early Friday.