TOKYO - Tropical Storm Meari lashed Japan's main island of Honshu with heavy rain on Saturday with further downpours forecast as it approaches the capital Tokyo.

Meari is forecast to dump as much as 300 millimetres of rain on parts of central Honshu, Japan's weather bureau said, threatening to disrupt the country's "bon" holiday period when many Japanese takes trips to visit family.

Bullet train services have been delayed and airlines including Japan Airlines and ANA Holdings cancelled flights, national broadcaster NHK reported.