The number of Japanese athletes at next year's Tokyo Olympics is expected to exceed 500 and could conceivably be one of the largest contingents in Olympic history, an informed source said Sunday.

The large number is credited to Japan's inclusion of baseball, softball, karate, sport climbing, skateboarding and surfing in Tokyo. As the host nation, Japan will also earn automatic berths in many team events, the source said.

Japan's largest team so far was the 355-member squad for the 1964 Tokyo Olympics, the only other time the nation has staged the summer games.

In addition to those competing in the core sports of the Olympic program, the sports added for Tokyo could swell Japan's team by as many as 67 athletes -- more than 10 percent of the team's total.

In addition, Japanese athletes will be able to compete in sports in which they rarely qualify. In handball, Japan's women will be in the Olympics for the first time since 1976, while the national men's team last took part in 1988. The two teams will contribute 28 members to the overall total.

Another 16 will be added through men's hockey, where Japan has not competed since the 1968 Mexico City Olympics.

Japan sent 338 athletes to Rio de Janeiro in 2016, where it failed to qualify for women's soccer as well as men's and women's beach volleyball. If Japan can qualify similar numbers in athletics and swimming events as it did in 2016, the total for next year could approach 600.

The July 24-Aug. 9 Olympics will stage a record 339 events in 33 sports. The Japanese Olympic Committee has set the host nation's gold-medal target at 30.