Tokyo's commuters faced packed trains due to delays, but there was little other impact after a strong earthquake rocked the Japanese capital, although authorities warned of aftershocks for up to a week.
The quake struck at 10.41pm local time on Thursday, centred just east of Tokyo and registering as a 'strong-5' on Japan's intensity scale, a level that could cause power cuts and damage to buildings.
The Japan Meteorological Agency revised down the magnitude to 5.9 from an initial rating of 6.1.
There were scattered reports of water-main breaks and about 250 buildings in downtown Tokyo briefly lost power.
One of the biggest commuter train stations, Shinagawa, lost power as well, forcing people into long lines for taxis as they tried to get home on Thursday night.
Several dozen people were injured, mainly by falls or being struck by falling objects. Most of the injuries were minor.
By Friday morning everything was back to normal except on some train lines that were running late or with limited capacity. Commuters overflowed into the streets due to crowding.
The Japan Meteorological Agency said aftershocks, possibly of similar strength, could occur for up to a week.
The hashtag "Because of the Quake", in Japanese, was trending on Twitter as Tokyoites, normally inured to tremors, tried to put the quake behind them by jokingly blaming it for everything from missing glasses to terrified cats.
"It looks like commuting is really crowded thanks to the quake," wrote one user.
"The only bit of luck in this is that most people have now had at least one dose of the (coronavirus) vaccine," they added.
Earthquakes are common in Japan, which accounts for about 20 per cent of the world's tremors of magnitude six or greater.
On March 11, 2011, an earthquake of magnitude nine - the strongest on record for the country - struck Japan's northeast coast, causing a massive tsunami and killing nearly 20,000 people.