Typhoon Ampil, categorised as "very strong" by the Japan Meteorological Agency (JMA), was situated off the Pacific coast of Japan's main island at 8:50 a.m. (2350 GMT Thursday). The agency has two higher categories - "very strong" and "violent".
The typhoon is expected to head towards the eastern region of Kanto, which includes the capital, on Friday afternoon.
Ampil has wind speeds of 45 metres per second with maximum gust of 60 metres per second (216 kph/134 mph), according to the JMA.
"The Kanto region is expected to experience fierce winds that could cause injuries from flying debris or even overturn trucks in motion," the JMA warned on its website.
Mobara City in Chiba Prefecture placed an evacuation order for about 18,500 residents, while dozens of other cities opened special evacuation centres and advised voluntary evacuation.
More than 2,000 households in the Kanto area were hit by blackouts in the morning before power was restored in some areas, the Tokyo Electric Power said.
ANA Holdings said it will cancel 281 domestic flights and 54 international flights slated to leave or arrive on Friday, affecting nearly 70,000 passengers.
Japan Airlines plans to cancel 281 domestic and 38 international flights, affecting about 50,000 passengers.
All the high speed "Shinkansen" bullet train services between Tokyo and Japan's industrial heartland of Nagoya are also cancelled.
People in parts of Japan are being told to evacuate, with some homes losing power on Friday as Typhoon Ampil approaches the coast near the capital.
The storm, located 121 nautical miles southeast of Yokosuka, Greater Tokyo, has intensified to the equivalent strength of a Category 4 hurricane, bringing winds of up to 212 kilometers per hour (131 mph) as it moves north at 18 kph (11 mph), according to the Joint Typhoon Warning Center (JTWC).
Ampil had rapidly intensified over the past two days, partly because it moved over very warm water – meaning more moisture in the air to fuel the typhoon. It could strengthen further in the next 12 hours, with the storm reaching peak intensity as it passes by Japan.
In the coastal city of Isumi, one of the areas expected to feel the brunt of the nearby storm by late Friday, authorities issued an evacuation notice to nearly 17,000 households – calling on the elderly and those with disabilities to evacuate, according to public broadcaster NHK.
A similar notice was issued in the city of Yokohama, south of Tokyo, with authorities warning that all residents should be prepared to evacuate.
