TOKYO (AP) _ More than 250 people have applied so far to compete in Japan's first international triathlon, a one-day competition that requires long-distance swimming and cycling and then a full marathon running race.

The Yanmar Ironman Japan '85 competition, to be run in and around Lake Biwa in western Japan, is scheduled for July 30. Of the 267 applicants, 43 are foreigners, mostly Americans, the organizers said.

The competitors are to swim 2.4 miles, cycle for 112 miles and run a full marathon of 26 miles, 385 yards.

Leading competitors include Americans Dave Scott, Scott Molina and Julie Moss.The top 100 finishers will be eligible to participate in the Bud Light Ironman Triathlon World Championship to be held in Hawaii later this year. ---

BOSTON (AP) - Veteran right-hander Bruce Kison was placed on a 21-day disabled list and right-hander Al Nipper was activated Monday by the Boston Red Sox.

Kison, signed as a free agent last winter, suffered a pulled left hamstring in warming up for his Boston debut against the Chicago White Sox Sunday. He lasted less than two innings, but was not involved in the decisions of Chicago's 11-6 victory.

Nipper, who had an 11-6 record after breaking into the starting rotation as a rookie last June, suffered an anemic condition traced to a stomach ulcer during spring training. He is due to start against the Royals in Kansas City Wednesday night. ---

EDEN PRAIRIE, Minn. (AP) - Tommy Kramer, who has been the Minnesota Vikings' No. 1 quarterback for the past several National Football League seasons, says he expects to be traded if University of Miami quarterback Bernie Kosar signs with the team.

''I doubt that we'll both be here next season,'' Kramer, 30, said Sunday. ''I figure if they sign him, I'd probably get traded. It would be nice to stay here, but it would be nice to go somewhere else, too.''

Kramer indicated he has no plans to play on a team where a backup quarterback would be earning more than he does.''Momma didn't raise no fool,'' Kramer told the St. Paul Dispatch and Pioneer Press.

A Kosar contract is expected to cost the Vikings $1 million a season, about $500,000 more than Kramer is to be paid next season. ---

NEW YORK (AP) - George Pfister, assistant to the administrator in the baseball commissioner's office, on Monday was honored for his ''long years of service to high school baseball programs and amateur baseball as a whole.''

Pfister, who was with the New York Yankees in a variety of positions, including farm director, before joining the commissioner's office in August 1974, received a plaque from Brice Durbin, executive director of the National Federation of State High School Associations.

Among his current duties, Pfister works on baseball's amateur June and Winter drafts. ---

POCATELLO, Idaho (AP) - Idaho State University head basketball coach Jim Boutin named two new assistants on Monday.

Allen Corder, formerly an assistant coach at University of Utah, is an ISU graduate. The 28-year-old Corder was starting guard for ISU 1978-79 and had 195 career assists.

Barry Janusch, 25, was head coach at Clark College in Vancouver, Wash. He played on newly named ISU coach Boutin's team at Western Oregon State College, where he graduated in 1981.

Janusch won All District II NAIA honors while playing for Boutin.