Large waves have caused water levels to rise across Japan after a massive earthquake off the eastern coast of Russia's Kamchatka Peninsula triggered a tsunami warning across the Pacific.
There have been no immediate reports of fatalities and injuries so far in Japan.
Japan's Meteorological Agency issued a tsunami warning for wide areas along the Pacific coast on Wednesday morning following the powerful earthquake.
The Fire and Disaster Management Agency under Japan's Ministry of Internal Affairs and Communications said that as of 17:00 on Wednesday, evacuation orders had been issued for over two million people.
Around 10:30 on Wednesday, the first tsunami waves reached Japan's northernmost island of Hokkaido, with Japanese media saying that waves of 0.3 to 0.8 meters were observed across the region.
Local residents sought shelter on rooftops and other elevated locations.
After reaching Hokkaido, the massive ocean waves struck the northeastern region of Honshu Island, with waves of 0.7 meters and 1.3 meters observed at Ishinomaki Port in Miyagi Prefecture and Kuji Port in Iwate Prefecture, respectively.
The tsunami then reached the Kanto region, including Tokyo, and coastal areas south of it.
At Kujukuri Beach in Chiba Prefecture, waves moved upstream into rivers.
Kujukuri and many other beaches across Japan are temporarily closed, as are some convenience stores, and some coastal railway lines and highways have suspended services.
On Wednesday afternoon, the meteorological agency warned that the tsunami risk is expected to remain high for at least another day, calling on coastal residents to stay in shelter until the tsunami alert is lifted.
Japan's Chief Cabinet Secretary Yoshimasa Hayashi said that no reports of damage to nuclear facilities have been received.
According to Japanese media, nuclear power plants took emergency measures on Wednesday.
Tokyo Electric Power Company issued evacuation instructions to workers at the Fukushima Daiichi and Daini nuclear power plants in Fukushima Prefecture, urging them to evacuate to higher ground. Fukushima Daiichi nuclear plant was severely damaged in the 2011 tsunami, with three of its reactors melting down and the discharge of radioactive water in to the Pacific, affecting hundreds of thousands of residents.
Nuclear power plants in Aomori, Ibaraki, and Shizuoka prefectures have also suspended outdoor work and asked workers to evacuate to safe places.
Currently, no abnormalities have been detected at any of the nuclear power plants.
Japan's Meteorological Agency has downgraded tsunami warnings to advisories for Ibaraki and Wakayama prefectures.
Tsunami hits Japan after major quake off Russia's Kamchatka
