Hundreds of thousands of Japanese citizens were advised to evacuate on Sunday as waves of more than a meter hit coastal areas, public broadcaster NHK reported, after the eruption of an underwater volcano off Tonga triggered tsunami warnings.
Around 230,000 people were advised to evacuate across eight prefectures due to the tsunami risk, NHK reported. The alert included areas hit by Japan's deadly 2011 tsunami.
Ten boats were capsized in Kochi prefecture on Shikoku island in southern Japan, NHK said, and Japan Airlines cancelled 27 flights at airports across the country.
The overnight disruption caused delays to rail and postal services in some areas, Kyodo News reported, with some residents passing a cold night after evacuating to higher ground.
A red tsunami warning - the second-highest in Japan's domestic scale - for Iwate prefecture in northern Japan was lifted late morning, NHK reported, although a less severe yellow tsunami advisory remains in place along Japan's eastern coast, with authorities continuing to urge caution.
An underwater volcano off Tonga erupted on Saturday, triggering warnings of 1.2-metre tsunami waves and evacuation orders on the shores of Tonga as well as several South Pacific islands. Footage on social media showed waves crashing into coastal homes.
Tonga, an island nation with around 105,000 residents, lies 2,383 kilometers (1,481 miles) northeast of New Zealand.
It remained largely uncontactable on Sunday with telephone and internet links severed, leaving relatives in faraway New Zealand praying for their families on the Pacific islands as casualty reports had yet to come through.
Internet and phone lines went down at about 6.40 p.m. local time on Saturday, leaving the 105,000 residents on the islands virtually uncontactable.
There are no official reports of injuries or deaths in Tonga as yet although communications are limited and contact has not been established with coastal areas beyond the capital Nuku'alofa, Jacinda Ardern the Prime Minister of New Zealand told a news conference on Sunday.
The Hunga-Tonga-Hunga-Ha'apai volcano has erupted regularly over the past few decades but Saturday's eruption was so loud that residents parts of faraway Fiji and New Zealand said they heard it.