In an attempt to boost its presence in the competitive Japanese computer market, Compaq Computer Corp. and Japanese subsidiary Compaq Computer KK have selected Canon Sales Co. to be their sole sales agent in Japan, the three companies announced Friday.Under the new agreement, Canon Sales, the sales unit of Canon Inc., will get exclusive rights to distribute the major U.S.-based computer manufacturer's new Presario personal computer series in Japan. The new PC is scheduled to debut here in late February.Canon will also participate in designing, developing and marketing a Presario targeted at Japanese users. Although Compaq achieved the top 13 percent share in the global PC market in 1997, the company has been struggling to expand in Japan due to its lack of a strong sales network, according to the firm.By concluding the agreement with the nation's major vendor, Compaq is seeking to increase its market share here from the current 3 percent, said Michael Heil, Compaq Computer Corp.'s senior vice president.The agreement will also be advantageous for Canon Sales, whose 50 percent share of PC sales was earned with the products of Apple Computer Inc., according to Canon Sales Chairman Seiichi Takikawa.The recent slowdown in sales of Apple computers has forced the company to look for stronger products, he said. "We have been selling Apple's products for nearly 15 years, but we are not sure how its share of the Japanese market will be in the future," Takikawa said. "We are grateful that we can also sell Compaq's computers."Canon Sales has been selling various companies' computers, including those built by Apple Computer and IBM Japan Co., and sold approximately 500,000 PCs last year.