A tropical storm formed about 620 miles southeast of Tokyo on Sunday and approached a remote Japanese island chain, Japan's Meteorological Agency reported.

Tropical Storm Usagi, located near the Northern Mariana Islands, with maximum sustained winds of 40 mph, was moving west at 19 mph, the agency said in a statement.

Usagi, which means "rabbit" in Japanese, is expected to hit Japan's Ogasawara island chain Monday afternoon, the agency said.

The storm was expected to continue traveling north-northwest and pass near Torishima Island, 360 miles south of Tokyo, by Wednesday. Agency official Toshiyuki Suzuki said it is not yet known where the storm would travel after that.

Typhoons and tropical storms frequently hit the region in the summer and fall, triggering deadly flash floods and landslides.

Earlier this month, a powerful typhoon skirted the Japanese capital and moved northeast after leaving three people dead and causing widespread flooding.